At this point in history when all things which concern man and the structure and elements of history itself are suddenly revealed to us in a new light, it behooves us in our scientific thinking to become masters of the situation, for it is not inconceivable that sooner than we suspect, as has often been the case before in history, this vision may disappear, the opportunity may be lost, and the world will once again present a static, uniform, and inflexible countenance.

Ideology and Utopia (1929)