Read in the wonderful collection The Permanence of Yeats (1950). Originally from the also wonderful Axel's Castle (1931).
"And in spite of the immense amount of poetry published and read to-day, the personality truly and naturally poetic seems to be becoming rarer and rarer. It may be true that the kind of dignity and distinction which have been characteristic of the poet in the past are becoming more and more impossible in our modern democratic society and during a period when the ascendancy of scientific ideas has made man conscious of his kinship with the other animals and of his subjection to biological and physical laws rather than of this relation to the gods. It was easy for the lyric poet, from Wyatt's age to Waller's, to express himself both directly and elegantly, because he was a courtier, or, in any case, a member of a comparatively small educated class, whose speech combined the candor and naturalness of conversation among equals with the grace of a courtly society. It was possible for him honestly to take up a residence in an intellectual world where poetic images stood for actualities because the scientific language and technique for dealing with these actualities had not yet come to permeate thought. But themodern poet who would follow this tradition, and who would yet deal with life in any large way, must create for himself a special personality, must maintain a state of mind which shall shut out or remain indifferent to many aspects of the contemporary world. This necessity accounts partly, I suppose, for Yeats's preoccupation in his prose writings, with what he calls the Mask or Anti-Self, a sort of imaginary personality, quite antagonistic to other elements of one's nature, which the poet must impose upon himself. It is hard to imagine a seventeenth-century poet being driven to such a theory -- a theory which makes one's poetic self figure as one of the halves of a split personality [. . . .]."