It is — I take it — a distinguishing characteristic of philosophy that it is everybody’s business. The man who is his own lawyer or physician, will be poorly served; but everyone both can and must be his own philosopher. He must be, because philosophy deals with ends, not means. It includes the question, What is good? What is right? What is valid? Since finally the responsibility for his own life must rest squarely upon the shoulders of each, no one can delegate the business of answering such questions to another. Concerning the means whereby the valid ends of life may be attained, we seek expert advice. The natural sciences and the techniques to which they give rise, though they may serve some other interests also, are primarily directed to the discovery of such means. But the question of the ultimately valuable ends which shall be served, remains at once the most personal, and the most general of all questions.
-C.S. Lewis, Mind and the World Order (1929)