F.A. Hayek, The Road to Serfdom

[T]here is little question that almost every one of the technical ideals of our experts could be realized within a comparatively short time if to achieve them were made the sole aim of humanity. There is an infinite number of good things, which we all agree are highly desirable as well as possible, but of which we cannot hope to achieve more than a few within our lifetime, or which we can hope to achieve only very imperfectly. It is the frustration of his ambitions in his own field which makes the specialist revolt against the existing order. We all find it difficult to bear to see things left undone which everybody must admit are both desirable and possible. That these things cannot all be done at the same time, that any one of them can be achieved only at the sacrifice of others, can be seen only by taking into account factors which fall outside any specialism, which can be appreciated only by a painful intellectual effort -- the more painful as it forces us to see against a wider background the objects to which most of our labors are directed and to balance them against others which lie outside our immediate interest and for which, for that reason, we care less.

[Chapter Four: The "Inevitability" of Planning]