In the human mind there is a resistless tendency to search into secret things, and to construct a philosophy of them. Aristotle gave us his _Categories_; the moderns try their hand in the same line of things. It means only this: men who are philosophers and thinkers seek to classify all facts and to find out and express--“formulate” is the word--a complete, all-embracing, all-explaining law of them. Witty Dr. Oliver Wendell Holmes, in his _Poet at the Breakfast-Table_, gives us a pretty satire on this invincible disposition and always disappointed and disappointing effort of thinkers. His “Philosopher” was ever just about to find expression for his great discovery--just about to state the all-comprehensive law, the perfect formula, that left out nothing and explained all. It is essentially a man’s way; in all departments we see the tendency and effort of men to explain the universe. The chemist talks of “atoms” because he wishes to get down to the basis of things--to know the ultimate fact, beyond which analysis cannot go. The ontologist talks of “germs” for a like reason; he is ever striving to find a something--a substance or a force--that will explain to him not one but every life process. And the greater ones are seeking always to explain the origin of all things--to show how the universe was started or got itself going. The philosopher who studies mind seeks the same sort of end--the construction of a mental science that embraces every fact and explains every mystery of mental action. The theologian is in the same drift; he wants a philosophy of religion. He seeks to explain God, and, in not a few instances, seems to labor more earnestly to show how God can save a sinner consistently with his own nature and government than to show the sinner how to be saved. The theologian labors to show what the origin of evil is, and to make his view a philosophy that will harmonize all differences and explain all mysteries.