Man cannot survive except through his mind. He comes on earth unarmed. His brain is his only weapon. Animals obtain food by force. man had no claws, no fangs, no horns, no great strength of muscle. He must plant his food or hunt it. To plant, he needs a process of thought. To hunt, he needs weapons,and to make weapons - a process of thought. From this simplest necessity to the highest religious abstraction, from the wheel to the skyscraper, everything we are and we have comes from a single attribute of man -the function of his reasoning mind.