What is musical vision? We all know the impression of a very heavy flash of lighting in the night. Within a second's time we see a broad landscape, not only in its general outlines but wity every detail. Although we could never describe each single component of the picture, we feel that not even the smallest leaf of grass escapes our attention. We experience a view, immensely comprehensive and at the same time immensely detailed, that we never could have under normal daylight conditions, and perhaps not during the night either, if our senses and nerves were not strained by the extraordinary suddenness of the event.
Compositions must be conceived the same way. If we cannot, in the flash of a single moment, see a composition in its absolute entirely, with every pertinent detail in its proper place, we are not genuine creators. . . . the creative musician, by reason of his earthly heritage, has to overcome many hurdles between them [visions] and their realization. . . . Not only will he have the gift of seeing -- illuminated in his mind's eye as if by a flash f lighting -- a complete musical form (though its subsequent realization in a performance man take three hours or more): he will have the energy, persistence, and skill to bring this envisioned form into existence, so that even after months of work not one of its details will be lost or fail to fit into his photomental picture. From "A Composer's World." Reprinted by permission of Harvard University Press, (c) 1952 by the President and Fellows of Harvard College.m