3. At first sight nothing would appear so profoundly varied, so essentially distinct, as the diverse substances which compose the world. Among the objects in art or nature which daily pass before our eyes, are there two objects which can be accused of a perfect identity? Is it not only a parity of composition? What dissimilarity at the point of view of solidity, of compressibility, of weight and multiple properties of bodies, between atmospheric gas and a thread of gold, between the aqueous molecules in the clouds, and those of the mineral which forms the bony framework of the globe! What diversity between the chemical tissue of the varied plants which decorate the vegetable kingdom, and that of the no less numerous representatives of animal life upon Earth!
However, we can state as an absolute and fundamental truth, that all substances known and unknown, however dissimilar they may appear, either in view of their constitution or in regard to their reciprocal action, are only different forms through which matter presents itself, only varieties into which it is transformed under the direction of the innumerable forces which govern it.