It works by drawing the general principles which ___1____ the facts, as they exist, and then by an intellectual survey of alternative possibilities which are ____2___ those principles. It enables men to construct an intellectual vision of a new world, and it preserves the zest of life by the suggestion of satisfying purposes. Youth is imaginative, and if the imagination be ___3____ by discipline this energy of imagination can in great measure be preserved through life.