  Santayana’s second moral insight is that for each animal the good is definite and final. There are specific goods for each animal depending on the specific heritable traits and interests of the psyche and on the specific circumstances of the environment. Self-knowledge, then, is the distinguishing moral mark. The extent to which one knows one’s interests, their complexity and centrality, will determine whether one can achieve a good life, provided the environment is accommodating. Santayana’s philosophy rests on his naturalism and on his humane and sympathetic appreciation for the excellence of each life. But from the perspective of autobiography, Santayana’s clear notion of self-knowledge, in the sense of the Greeks, is his most distinguishing mark. For Santayana, “integrity or self-definition is and remains first and fundamental in morals …” (Persons and Places 170).