But let us not be disturbed by this problematic entrance to our studies. Let us follow biology on its own path; let us study its transition from a “naïve” science to a real branch of the philosophy of nature. In this way we perhaps shall be able to understand what its part may be in solving what can be solved. That is to be our subject. OUR PHILOSOPHICAL BASIS We call *nature* what is given to us in space. Of course we are not obliged in these lectures to discuss the psychological and epistemological problems of space with its three dimensions, nor are we obliged to develop a general theory of reality and its different aspects. A few epistemological points will be considered later at proper times, and always in connection with results of theoretical biology. At present it must suffice to say that our general philosophical point of view will be idealistic, in the critical meaning of the word. The universe, and within the universe nature, in the sense just defined, is my phenomenon. That is what I know. I know nothing more, either positively or negatively; that is to say, I do not know that the world is *only my* phenomenon, but, on the other hand, I know nothing about its “absolute reality.” And more, I am not even able to describe in intelligible words what “absolute reality” might mean. I am fully entitled to state: the universe *is* as truly as I am--though in a somewhat different sense of “being”--and I *am* as truly as the universe is; but I am not entitled to state anything beyond these two corresponding phrases. You know that, in the history of European philosophy at least, Bishop Berkeley was the first clearly to outline the field of idealism.