The cat is the only animal which accepts the comforts but rejects the bondage of domesticity.

Man thinks, and at once becomes the master of the beings that do not think.

As historians, we refuse to allow ourselves these vain speculations which turn on possibilities that, in order to be reduced to actuality, suppose an overturning of the Universe, in which our globe, like a speck of abandoned matter, escapes our vision and is no longer an object worthy of our regard. In order to fix our vision, it is necessary to take it such as it is, to observe well all parts of it, and by indications infer from the present to the past.

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.

Time is the great workman of Nature.

Let us investigate more closely this property common to animal and plant, this power of producing its likeness, this chain of successive existences of individuals, which constitutes the real existence of the species.

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.