In the preface to _The Wild Swans at Coole_,[3] Mr W.B. Yeats speaks of 'the phantasmagoria through which alone I can express my convictions about the world.' The challenge could hardly be more direct. At the threshold we are confronted with a legend upon the door-post which gives us the essential plan of all that we shall find in the house if we enter in. There are, it is true, a few things capable of common use, verses written in the seeming-strong vernacular of literary Dublin, as it were a hospitable bench placed outside the door. They are indeed inside the house, but by accident or for temporary shelter. They do not, as the phrase goes, belong to the scheme, for they are direct transcriptions of the common reality, whether found in the sensible world or the emotion of the mind. They are, from Mr Yeats's angle of vision (as indeed from our own), essentially _vers d'occasion._
[Footnote 3: _The Wild Swans at Coole_. By W.B. Yeats.(Macmillan.)]
The poet's high and passionate argument must be sought elsewhere, and precisely in his expression of his convictions about the world. And here, on the poet's word and the evidence of our search, we shall find phantasmagoria, ghostly symbols of a truth which cannot be otherwise conveyed, at least by Mr Yeats. To this, in itself, we make no demur. The poet, if he is a true poet, is driven to approach the highest reality he can apprehend. He cannot transcribe it simply because he does not possess the necessary apparatus of knowledge, and because if he did possess it his passion would flag. It is not often that Spinoza can disengage himself to write as he does at the beginning of the third book of the Ethics, nor could Lucretius often kindle so great a fire in his soul as that which made his material incandescent in _Æneadum genetrix_. Therefore the poet turns to myth as a foundation upon which he can explicate his imagination. He may take his myth from legend or familiar history, or he may create one for himself anew, but the function it fulfils is always the same. It supplies the elements with which he can build the structure of his parable, upon which he can make it elaborate enough to convey the multitudinous reactions of his soul to the world.