Nature is the system of laws established by the Creator for the existence of things and for the succession of creatures. Nature is not a thing, because this thing would be everything. Nature is not a creature, because this creature would be God. But one can consider it as an immense vital power, which encompasses all, which animates all, and which, subordinated to the power of the first Being, has begun to act only by his order, and still acts only by his concourse or consent ... Time, space and matter are its means, the universe its object, motion and life its goal.

All the work of the crystallographers serves only to demonstrate that there is only variety everywhere where they suppose uniformity ... that in nature there is nothing absolute, nothing perfectly regular.

The discoveries that one can make with the microscope amount to very little, for one sees with the mind's eye and without the microscope the real existence of all these little beings.

There are several kinds of truths, and it is customary to place in the first order mathematical truths, which are, however, only truths of definition. These definitions rest upon simple, but abstract, suppositions, and all truths in this category are only constructed, but abstract, consequences of these definitions ... Physical truths, to the contrary, are in no way arbitrary, and do not depend on us.

The greatest marvel is not in the individual. It is in the succession, in the renewal and in the duration of the species that Nature would seem quite inconceivable. This power of producing its likeness that resides in animals and plants, this form of unity, always subsisting and appearing eternal, this procreative virtue which is perpetually expressed without ever being destroyed, is for us a mystery which, it seems, we will never be able to fathom.

We can only penetrate the rind of the earth.

Genius is simply patience carried to the extreme.