Even among the philosophers of science, there have been many different attitudes toward the nature of biological thought. Some are provincialists and hold that at best biology is a province of physical science. By contrast with provincialists, some philosophers, called autonomists, advocate the autonomy of biological science. Although we can easily find differences between physical science and biological science, it is a question of whether or not there is the essential difference between them. As a gradual autonomist, I pick up two things, symbolic objects and the confirmation in terms of matching. From the fact that biologists usually study only some aspects of objects, I show that objects in biology are not the usual objects in our sense but the symbols or the structures. Verification and matching might be the same concept, but I stress the intuitive initial grapsing of phenomena and the programming of their biological reconstructions. Symbols as biological objects and matching show us the nature of biological rule which is different from natural law. To justify biological rules, I rely on the concept of descent. Descent of rules have been analyzed by the theory of evolution. It follows that the theory of evolution is not only a biological theory but also the foundational theory of biology, just as set theory in mathematics.