In 1934, Nicolle published the final book in his biological/philosophical trilogy. La Nature: Conception et Morale Biologique [Nature] opens with the author's personal invitation to the reader to accompany him in his narrative explorations. More specifically, he summons the reader to join him at a window, looking out over “nature”: “We approach the window. I open it. Reader, you lean on the sill next to me.” Outside, the garden is coming to life; “beyond it, the sea gently stirs up its pebbles.” Inspired by the scene, Nicolle proclaims, “ ‘Nature is beautiful.’ You add,‘She is caring [aimant].’ “ Nicolle and his reader return to the window in winter.The cold wind chills them. “Now invisible, the roaring sea hurls its waves.” The garden is in ruins. “I say, ‘Truly nature is ugly.’You add,‘Worse, she is cruel to all living things.’ “ How, then, does one reconcile these contradictory observations, made of the same place, if in different times? “Beauty and benevolence; the ugliness and evil that we define as their opposites, are but the sentiments with which we clothe nature. Intelligence, absurdity: it is our human judgment that so labels it. Nature is neither beautiful nor ugly, neither good nor bad. It does not know reason or illogic. It is.” It is from this “nature” that Nicolle, in the book Nature, seeks to explain human civilization. What, within such an animate but deanthropomorphized nature, could possibly give rise to logic and intuition, to perceptions of beauty, goodness, and truth, or to the visceral need for justice to prevail?

Three decades earlier, Nicolle had believed that human civilization could master nature. He had embraced the Baconian dream of a world in which knowledge, properly obtained, conferred such power. This dream not only gave force to his ideas of what might be achieved; it also helped propel both Pastorian and French civilizing missions. Long wary of reason detached from empirical observation, after World War I, Nicolle increasingly saw limitations in the power of scientific reasoning as well. Eventually, he emphasized the role of “intuition” in his formulation and added “equilibrium” to give it vital flexibility.This was his vision in Biologie. By the time Nature appeared, even this vision had paled.