Thinking is a vital, practical function that helps creatures, both humans and animals, to withstand the eternal war between it and the forces of nature that do not know how to retreat. This is because nature alone does not guarantee its victory. But the difference between human thinking and animal thinking is not only a difference in rank or quantity, but rather a difference in quality or quantity as well. Animal thinking is entirely practical, it is entirely a means to action. But man goes beyond these utilitarian limits and sometimes inquires for the sake of knowledge itself, and reaps from that pleasure no less than the physical pleasures he reaps from his other instinctive inclinations. Therefore, man was the only being who sometimes thought in order to think for himself.