Now this circumscribed power, which we have scarcely examined, scarcely studied, this power to whose actions we nearly always attribute an intention and a goal, this power, finally, that always does necessarily the same things in the same circumstances and nevertheless does so many and such admirable ones, is what we call 'nature' .

What nature does in the course of long periods we do every day when we suddenly change the environment in which some species of living plant is situated.

It is not the organs-that is, the character and form of the animal's bodily parts-that have given rise to its habits and particular structures. It is the habits and manner of life and the conditions in which its ancestors lived that have in the course of time fashioned its bodily form, its organs and qualities.

Habits form a second nature.

All known living bodies are sharply divided into two special kingdoms, based upon the essential differences which distinguish animals from plants, and in spite of what has been said, I am convinced that these two kingdoms do not really merge into one another at any point.

The thesis that the living creatures have always been composed different species was established in a time where no sufficient observations had been made and when science hardly existed. This thesis is denied every day by those who have made accurate observations, who have long time observed nature and who have had the benefit from studying our musei's large and rich collections.

Life, in a body whose order and state of affairs can make it manifest, is assuredly, as I have said, a real power that gives rise to numerous phenomena. This power has, however, neither goal nor intention. It can do only what it does; it is only a set of acting causes, not a particular being. I was the first to establish this truth at a time when life was still thought to be a principle, an archeia, a being of some sort.