Each thought has a size, and most are about three feet tall, with the level of complexity of a lawnmower engine, or a cigarette lighter, or those tubes of toothpaste that, by mingling several hidden pastes and gels, create a pleasantly striped product. Once in a while, a thought may come up that seems, in its woolly, ranked composure, roughly the size of one’s hall closet. But a really large thought, a thought in the presence of which whole urban centers would rise to their feet, and cry out with expressions of gratefulness and kinship; a thought with grandeur, and drenching, barrel-scorning cataracts, and detonations of fist-clenched hope, and hundreds of cellos; a thought that can tear phone books in half, and rap on the iron nodes of experience until every blue girder rings; a thought that may one day pack everything noble and good into its briefcase, elbow past the curators of purposelessness, travel overnight toward Truth, and shake it by the indifferent marble shoulders until it finally whispers its cool assent—this is the size of thought worth thinking about.