The Wanderings of Oisin and The Countess Kathleen both derived from Yeatss decision, which was taken quite deliberately when he was about twenty, to make himself an Irish poet. He went to ancient mythology for The Wanderings of Oisin and to a supposedly Irish folk-tale for The Countess Kathleen and drew as well upon the same type of material for its immediate successor The Land of Hearts Desire (1894) ; these were the two principal sources at which the Irish imagination might strengthen itself by drinking at the fountains of its youth and the traditions kept alive amongst the people. In the reviews which he wrote for American journals between 1887 and 1892 he insisted that Irish writers must stick to Irish subject matter - ‘We peer over the wall at our neighbors instead of making our own garden fresh and beautiful; and that they must get to know the literature of the imaginative periods of Irish history. When folk-tales and the speech of the Irish peasant are reported, the bad nineteenth-century tradition of steeping everything in a kind of stage Irish in order to gratify the expectations of the foreign reader must be abandoned. Yeats read very widely for his three anthologies of nineteenth-century Irish literature: Fairy and Folk Tales of the Irish Peasantry (1888), Stories from Carleton (1889), and Representative Irish Tales (1891). He found much to admire in a humour  whose essence was dare-devilry and harum-scarum gentility and in the pathos and ‘gentle Arcadian beauty of the folk-tales of Crofton Croker whose Fairy Legends and Traditions (1825) was the first of numerous later collections of folklore. But both the novelists and the folklorists were, in Yeatss view, injured by their narrow conception of Irish life; in Crokers hands, the sidhe, the gods of the earth, ‘dwindled to dancing mannikins; in the works of Lover or Lever the stage Irishman is substituted for the serious passions and convictions of the true peasant; and even Carleton, the great novelist of Ireland, ‘like the animals in Milton, half-emerged from the earth and its brooding, was forced ‘to write for a class who wished to laugh a great deal, and who did not mind weeping a little, provided he allowed them always to keep their sense of superiority. [Stories from Carleton, p.xvii; Representative Irish Tales, p.9.]
Upon the anthologies ensued not only Oisin and Kathleen but Yeatss own collection of folklore The Celtic Twilight (1893, revised and enlarged 1902). Many literary currents, the work of the translators of mythological literature, of Standish OGrady, Samuel Ferguson, Douglas Hyde, and the inspiration of the Fenian leader John OLeary, with whom Yeats was very closely associated, flowed in favour of the movement to go down amongst the people and listen to what they had to say. But for Yeats, behind all this overt policy and exercising a deeper constraint, lay the landscape of his Sligo childhood and the country stories of the Middletons, the spirit at Rosses that looked like a flat-iron, and Mary Battle, his Sligo uncles servant who had the second sight. ‘Much of my Celtic Twilight is but her daily speech. [Autobiographies, 1955, p.71.] Most of the pieces began as sketches for periodicals, and the book presents no grand design. But besides being a collection of folk-stories and superstitions it is a chapter of autobiography. Interwoven with these elements is a third: visionary meditation on the stories and places, so that we feel throughout the book the constant pressure of  Yeatss impulse to transcend his folk-tale material: ‘to show in a vision something of the face of Ireland. [Collected Works, 1908, I, p.1.] It is not ‘systematical and learned, as Douglas Hydes admired collection Beside the Fire (1891) had been, but ‘a handful of dreams:
Three sections that follow upon one another may illustrate the method. “Village Ghosts” is a plain collection of little anecdotes, some with the sort of humour, some with that frisson that characterises Yeatss best stories of this sort, all told detachedly and inconclusively. “A Knight of the Sheep”, its title suggested by Gerald Griffins tale which had been included in Representative Irish Tales, is about Katharine Tynans father the ‘strong farmer, and is a sliver from the nineteenthcentury novelists tradition. [Cf. Tynan, Twenty-five Years, 1913, pp.7-8.] In between these two, “Dust hath Closed Helens Eye” presents the image that was made permanent in the second part of “The Tower”, of Thoor Ballylee, Mary Hynes, and Raftery:
Here the old, poor, half-blind poet, the ‘handsomest girl in Ireland, and the landscape of Ballylee are linked with the mythology of Troy and wrought into a symbol of the ‘sorrow of beauty and of the magnificence and penury of dreams. Yeats begins with the remembered fragments  of peasant talk and local wonder, the imaginative care for the past residing in humble description, and ascends from them, out of the ‘soil where all great art is rooted, into fable. “Dust hath Closed Helens Eye” is written, as nearly twenty years later was The Only Jealousy of Emer, for ‘some country where all classes share in a half-mythological, half-philosophical folk-belief which the writer and his small audience lift into a new subtlety. [Four Plays for Dancers, 1921, p.106.] All his life Yeats longed for such a country. The principle at work in The Celtic Twilight and its companion-piece The Land of Hearts Desire is clearly stated in one of the earliest reviews:
Yeatss quest for universalism dominates a series of major essays composed in the eighteen-nineties and collected together in Ideas of Good and Evil (1903) as well as the three volumes of The Works of William Blake (1893), done in collaboration with Edwin Ellis. The quest arose first from a sense of deprivation: the feeling that the unity of man and nature had burst into fragments and that reason, science, and the abstracting mind of the Anglo-Saxon had exiled human emotion from mans understanding of the universe. So he turns away from speculation and the ‘vegetable glass of Nature, ‘where the heart withers, to the imagination as it is embodied in the words of the poets and in dreams and magical visions: ‘for I am certain that the imagination has some  way of lighting on the truth that the reason has not. [Essays & Introductions, p.65.] For Yeats the finding of this way entails a search for the ‘symbolic correspondences which Swedenborg and Blake had named and which make it intelligible to say that ‘the hailstone is a journeyman of God, because such a statement is a ‘seeing of unity; it apprehends in vision, in emotion and intellect conjoined, the divine order of the whole universe. Wisdom of this kind speaks first in symbols. These are not ‘isolated artistic moments, mere metaphors which do not carry any charge of unfolding meanings, but ‘signs or representations of any moral thing by the images or properties of natural things (Yeats accepts, with some reservations, the dictionary definition, in his essay on “The Symbolism of Poetry”). The symbol may be a hailstone, or a blade of grass, or a grain of Irish sand; to contemplate it rightly and lovingly, as the poet or mystic or visionary do, is not to study the Blakean ‘vegetable glass for its own sake but to discover the shadow of imperishable things and substances and to find the road into ‘some divine labyrinth.[Essays & Introductions, p.117.] Such symbols may be found also in the natural world, in the poets, and in traditional objects of worship and contemplation which also have stirred the intellect and evoked the emotions of men throughout the ages:
Such a passage gives some notion of what Yeats meant when he spoke of the symbols as ‘an endlessly intermarrying family; Dante or the mythological tale ‘cannot tell one thing without telling a hundred others [Works of William Blake, I, p.282-83] (the principle is at work in The Wanderings of Oisin); for he agreed with Arthur Symons that symbolism is the ‘establishing of the links which hold the world together. [Symons, The Symblist Movement in Literature, 1899, p.146.] Like Hopkinss bluebell or De la Mares snowdrop, such symbols or families of symbols (‘the procession of the symbols) give Yeats news, if not of the creator God, then of the intricate harmony of the universe, a ‘divine labyrinth, which the imagination, itself become part of the family, both creates and receives when it is undistracted by business or reason and perhaps intensified by  magical practices or ascetic disciplines. The symbols that carry furthest and multiply most vigorously in the mind with their own life are those that awaken both intellect and emotion. A symbol that is associated merely with an idea provides only a moments amusement or leads straight to allegory, which is an operation of abstracting reason; a symbol that is purely emotional leaves us in the Keatsian sweetshop, the mere profusion and sweetness of nature, in the ‘sleep of nature where all is soft and melting, and tempts the artist away from the ‘labours of inspiration. But Nature, the delusive goddess, is, in Blakean phrase, a ‘net woven by Satan [Essays & Inroductions, p.132.] Yeats believes with Samuel Palmer, Blakes disciple, whom he was also studying at this time, that the soul must climb above her steepest summits, and that the artist must choose not to ‘see like a naturalist but to see everything, even a man talking or gesturing, as ‘expressive and symbolic ... every form, every sound, every colour, every gesture, a signature of some unanalysable imaginative essence. [The Life and Letters of Samuel Palmer, 1892, p.43.] And so amongst the poets Yeats chooses not Shakespeare but Dante, not Morris, a worshipper of natural abundance, but Rossetti and Shelley, not Wordsworth but Blake; and he chooses occultism, not philosophy, as at once a source of symbols and a means of proving to himselfthe minds capacity for ‘establishing the links.
The endlessly intermarrying families and the tales that tell a hundred things threaten to become a mere disorder in the mind, as bad as Natures profusion: but ‘true Unity of Being, where all the nature murmurs in response if but a single note be touched, is found emotionally, instinctively, by the rejection of all experience not of the right quality, and by the limitation of its quantity. The getting of his mind into order was, Yeats told his father, the real impulse to create. It can be seen at work in the essay on “The Philosophy of Shelleys Poetry” and, on a much larger scale, in the  edition of Blake. In both we can observe his continual acknowledgment of Blakes command to ‘set his symbols in the great procession ... in a certain order, suited to his ‘imaginative energy. [Essays & Inroductions, pp.149-50.] He transformed into order the poetry of Shelley, who was so often the victim, in Yeatss own judgment, of rootless fantasy, by massing and linking together Shelleys recurring images of wonder - cave and fountain and tower - and so produced a world which grew solid underfoot and consistent enough for the souls habitation. Some one scene, adventure or picture, he says at the end of the essay on Shelley, can, if but brooded over for a whole life, disentangle the soul; perhaps this can only be properly done by the systematic mystic, for the poet is caught up in the circumstances of his art. Yet the mystic or occultist may help the poet to transform his mind, too, into a burning-glass. Yeats would have liked to be a seer as well as a poet; the dialogue between them became his subject-matter.
Yeatss choice and limitation of symbols are illustrated in the poems he wrote during the eighteen-nineties, grouped in the section of Collected Poems entitled “The Rose” and in the volume The Wind Among the Reeds (1899).
Nature in these poems is symbolical, never described for its own sake, and limited to the four elements or their expression in woods, waves, winds or stars. The Irish mythological figures, too, are dislimned into elemental beings, spirits of the four elements. The chief relation celebrated is that of the lover to his mistress and beyond her or through her to a nature and a universe, which constantly interconnect with or mirror his emotional moods, his fears and desires, in their flame or flood, their tides and clouds and trees. Because the theme is limited in this way, and because of the severe restrictions on the emblems and properties, including the diction, the two collections achieve a general unity of tone, but at a price. Earth, air, water, fire, their creatures, conjunctions and  oppositions are constantly interwoven through the poems, like the recurring patterns in an Indian carpet. Yeats handles them as arabesques, as though some tabu forbade him to represent the whole human image: pale waters, white stars, dim grey sea, white birds, burning hair, desolate winds, grey twilight, flaming West, pale dew, dim sand, cloud-pale eyelids. When these bits are put together into their pattern, in individual poems, or in the mind of the reader as he surveys the poems as a whole, nothing resembling a felt, natural or psychological landscape emerges: what we have instead is a demurely restricted language, of which the words are these symbols, and which, we apprehend, is being spoken by a rather shadowy persona. It is strange work to have come from a pupil of Blake, from those naked, sinewy bodies. Yeats uses his language of symbols, not for communicating but for crooning over in his head. He holds himself a little out of our reach, a priest at the altar, his back turned to us, invoking in ways that move him deeply but obscurely; and though he changes his name from Aedh to Hanrahan to Michael Robartes (here all aspects of the lovers imagination), the roles are played out in a dream, with closed eyes. When the Rose, the central symbol of the Order of the Golden Dawn (the Incorruptible Beauty, womans beauty, the rose of peace, of battle, and in the poem called “The Secret Rose” the symbol of the coming change of all things), appears in the imagination, the posture of worship is more extreme, for this is a secret symbol unlike the more traditional four elements: but the voice, though its volume rises, is still a voice in the head. It is their rhythmic beauty, their wavering enchantment of line, and their modesty of proportion, a keeping of scale, that makes these poems professional; it is that kind of seriousness which now appears as a specific symptom of poetic power - a matter of decorum and of rhetoric, coupled with inborn rhythmic sense. 
This half-silent, tapestry-like verse sets the standard from which one or two poems in the “Rose” section depart-notably “The Man who Dreamed of Fairyland”, with its firm structure, its objectification of the character described, and even in its earliest version, its unsleepy lines (‘that cold and vapour-turbaned steep). “The Two Trees”, a poem about Maud Gonne, the Tree of Life and Imagination, and the Tree of Knowledge and Death, by its directness of address and its splendidly articulated cabbalistic and Blakean symbolism does build an ‘image of wonder. It is because on this occasion we see and participate in the building process that “The Two Trees” draws us in with its own energies. Also, in the way in which it handles in verse what was to become a dominant idea the poem is a prophetic one. In this case the idea is that a beautiful woman should not despoil the subjectivity of her nature by the politics of objectivity, or sacrifice the unity of her being to a cause outside itself; this subject is anticipated in The Countess Kathleen and fully presented in such later poems as “A Prayer for my Daughter” and “In Memory of Eva Gore-Booth and Con Markiewicz.”
The place of ideas of this kind in Yeatss work is worth trying to define here, because so many of them were formed before the turn of the century, and remained with him always. He tells us in The Trembling of the Veil that he was ashamed of the way in which generalisations flooded his mind in his twenties; he could not ‘choose from among them those that belonged to my life, [Autobiographies, p.83.] and would not permit them into his poetry because they arose from the ‘intellect which I considered impure [Ibid., p.188]; as a result the poetry turned sentimental. But:
The ‘conviction is a personal discovery, accepted upon an inward authority, and ‘tested by passion. Poetry, Yeats discovered, which excludes the intellect becomes sentimental, empty and fantastic; poetry cannot be separated from philosophy and belief, but it can incorporate them by portraying ‘the emotions of a soul dwelling in the presence of certain ideas. Richard Ellmann, who has provided a valuable account of this matter in the third chapter of his Identity of Yeats, has summed it up in the phrase “Assertion without Doctrine”; he describes Yeatss finally matured practice in this way:
A list of Yeatss ‘convictions divorced from the poetry, even if they were largely formed as ‘generalisations before most of the poetry incorporating them was written, is therefore likely to be misleading. It is even more dangerous to use the poems merely as ciphers for decoding the generalisations. But it is a fact of the biography,  which can be discovered from the prose-writings of the eighteen-nineties and from the retrospective accounts of the period in the Autobiographies, that many of the thoughts were shaped in these years, and only needed separation from momentary opinions and the testing of their value by time and passion to become convictions and to be used as assertions in the later verse - for in this context, time is passion: an idea held for long enough becomes a portion of the affective self.
The ‘necessity for symbolism was such a thought, as was the decorum of the Irish setting; both of them closely connected with a third: the conviction that the ‘world was now but a bundle of fragments and that the enemy of its lost and desired unity of being, in the individual, the nation, and the arts, was abstraction, that seeks to cage the ‘yellow-eyed hawk of the mind and destroy the absorption in a unifying image. From magical and theosophical studies, and from such ‘sacred books as Villiers de lIsle Adams Axel Yeats took many other generalisations; he is not often so frankly credal in expressing them as when he describes his belief in the ‘great memory in the first paragraph of the essay on “Magic” (1901); for, just as Yeats, as Ellmann puts it, ‘relies on the complexity of poetic structure to prevent his verse from becoming doctrinal [Op. cit., p.55.] so he relies on a powerfully rhythmical and metaphorical prose-style and an oracular rather than dialectical handling of the themes to prevent his essays or stories ceasing to be primarily works of art. Yet in these writings can be traced many later poetic ‘assertions and ‘convictions. Two of the most important are the notion of a coming change in the world, signalised by Mallarmés phrase about the ‘trembling of the veil of the Temple before it is rent in interlocking catastrophe and revelation, and of rebirth and its counterpart, the hope of escape from the round of incarnations into a changeless and immortal existence. 
The first idea enters into several of the stories in The Adoration of the Magi and The Secret Rose (1897), volumes which, as Giorgio Melchiori has shown, ought not to be neglected by anyone concerned to understand the origins of “The Second Coming” (192o) or “Leda and the Swan” (1924), not to mention such plays as The Player Queen (1922) and The Resurrection (1931). Yeats used the theme at the same time in “The Valley of the Black Pig” ( 1896), but it is characteristic of his attitude to his poetry at this time that the long note he wrote for this poem in The Wind Among the Reeds [1899, pp.95-102] is much more lovingly explicit about its subject than the vague little lyric. Comparatively explicit, too, is “The Adoration of the Magi” where the new magi are summoned from the west of Ireland to the bedside of a dying prostitute in Paris to learn from her the secret names of the returning gods. When Yeats revised the story for publication in 1925 the prostitute has become more explicitly still the harlot of the new annunciation [Mythologies, p.312], another Leda, but even in its first version Virgils prophecy of the cyclical return of civilisations is present in anticipation of the song in The Resurrection . [Coll. Works, VII, 170; Coll. Plays, p.580.] In the speech given, after the harlots death, to the old woman who has been attending her - a speech full of scepticism and bewilderment - we can see Yeatss willingness to make even this portentous material, in which his imagination and intellect were so deeply engaged, part of a dramatic scene. [Coll. Works, VII, p.176.] This principle is of the utmost importance for the understanding of how Yeats uses his ideas in his best plays and poetry, as expressions of the ideas of the personae, rather than as doctrines demanding the readers assent. The alchemical stories “Rosa Alchemica” and “The Tables of the Law” obey the principle perhaps most obviously by being, frankly, stories. The narrator in “Rosa Alchemica”, dissatisfied in the midst of a life modelled on that of Des Esseintes, restless for the final wisdom amongst his preciously garnered symbols, is, in the manner of some  prototypical Synge, mesmerised by the alchemical initiate Michael Robartes into travelling (by train and boat) to the west of Ireland, of all places, in order to learn truth by alchemical ritual. But he ends by fleeing in disorder from the Temple of the Alchemical Rose, and thenceforth carries the rosary about his neck and a heart divided between the terror and the fascination of what may be only ‘the illusions that creep like maggots into civilisations when they begin to decline, and into minds when they begin to decay. [Coll. Works, VII, p.117.] Similarly in “The Tables of the Law” (Aherne and another devout, but disturbed, narrator are the persons) a dramatic dialectic is made out of the conflict between old orthodoxy, whose prophet is Jesus, and the new revelation, whose prophets include Joachim of Flora, Jonathan Swift and the Pre-Raphaelites. And these safely dramatised stories were written not long after a period when Yeats was causing concern to his father and his friends by what seemed too intense and total an absorption in the mysterious affairs of the Order of the Golden Dawn.
But they need not have worried. Yeats was already convinced that ‘picture and dramatization were his primary concern; he was an artist first and last and never lost pleasure and pride in being one. From beginning to end this shines through the great collection of his letters: to write, to print, to revise, to be a man of letters - Yeats never seriously lost his zest for the role, as had some other great romantics before him. Much in his early work both as it succeeded and failed - the failure or absence of the persona in the early poems, the invention of the characters in the stories and of the elaborate stylist who wrote the essays, the faintly emergent protagonists of The Wanderings of Oisin and The Countess Kathleen - point straight towards the literal interpretation of his concern for picture and dramatisation as a need for the theatre itself, for characterisation and for ‘stage-picture:
Among the things that dramatic action must butn up are the authors opinions; while he is writing he has no business to know anything that is not a portion of that action. [Letters, ed. Wade, 1954, p.741.]