Schopenhauer's works: 18 13 "On the Four Roots of the Law of Sufficient Reason"; 18 16, on vision and color; 18 19 as the world of will and representation puts forward that "the world is my representation". He confused the objective world with the subjective world. On this basis, he completed his philosophy system of voluntarism: will (thing itself)-concept (direct objectification of will)-thing (indirect objectification of will) 1836 On Will in Nature; 1839, on freedom of will; 1840, on the basis of morality; 184 1 two basic problems in ethics; 185 1 year, appendix and addendum; Pessimistic color "Life is a pendulum between pain and boredom".