In distilling, the small amount of alcohol evaporated during the aging process is known as the angels' share. at is, while lost to us, the alcohol does not cease to exist, but instead is given to -- or taken by -- the angels.

Architecture's own angels' share--the notion of an absent and intangible other--has too been personi ed. From Genius Loci to Zeitgeist, the gure of the spirit is perhaps the most fundamental component of architecture, even before walls or columns. Whether phenomenal or conceptual, without this ickering spirit, one might say, there is no architecture. As technology...