All men, says Aristotle, have a natural desire for knowledge. The need for knowledge is a law of our mind. Just as hunger and thirst urge upon man the necessity of satisfying his desire for nourishment so as to safeguard the conversation and development of his physical being, in the same way a nobler appetite unceasingly stimulates his intellect and prevents it from ever forgetting that he needs the food of truth if he wants to attain to the perfection of his human nature. Thus the desire for knowledge is innate in the human mind. It manifests itself in the many whys and hows which the child never tires of asking, since even in the most humble state of its evolution the human intellect feels the need for a certain totality of understanding....