The Metaphysics of Life: From Leçons de Psychologie et de Métaphysique given at Clermont-Ferrand, 1887-88

Let’s now rise now above matter per se, and let’s inquire into what characterizes the living being. There are many theories on the nature, origin and essence of life; we will begin with the most simple, which denies that life is something sui generis, and which claims to reduce vital phenomena to physical and chemical facts like any others. First, there is one point upon which everyone agrees: vital phenomena present characteristics that seem so distinct from those of inert matter that we have invented a new name to distinguish them; thus nobody questions the appearance of phenomena sui generis. What are these phenomena? At first glance, what distinguishes the living body from brute matter is the presence of an apparent capacity to react against physical and chemical forces—a kind of initiative. A mere body [corps brut], left to itself, necessarily suffers the inevitable action of gravity, of heat, or of any other physical force. The phenomenon is entirely and absolutely determined in each identical situation by the conditions to which it is exposed; this can be foreseen with mathematical certainty and precision. But when we consider life itself in its imperfect, rudimentary state—even in those vegetables about which it cannot be said precisely if they are living or not living—new characteristics appear. Here we cannot foresee mathematically what will happen. Two seeds placed in the same ground and that present the same aspect to scientific observation will not behave in the same way. Even setting aside this point (which could in fact be contested), we will maintain that if two organized beings, although identical in appearance, do not develop in the same way, that is because certain conditions, which we cannot perceive with our means of observation, exist.