It is almost impossible to conceive that our world with its satellite, and its fellow worlds with their satellites, and also the great centre of them all, have always, from the commencement of time, possessed their present form: all our experiences of the working of natural laws rebel against such a supposition. In every phenomenon of nature upon this earth—the great field from which we must glean our experiences and form our analogies—we see a constant succession of changes going on, a constant progression from one stage of development to another taking place, a perpetual mutation of form and nature of the same material substance occurring: we see the seed transformed into the plant, the flower into the fruit, and the ovum into the animal. In the inorganic world we witness the operation of the same principle; but, by reason of their slower rate of progression, the changes there are manifested to us rather by their resulting effects than by their visible course of operation. And when we consider, as we are obliged to do, that the same laws work in the greatest as well as the smallest processes of nature, we are compelled to believe in an antecedent state of existence of the matter that composes the host of heavenly bodies, and amongst them the earth and its attendant moon. In the pursuit of this course of argument we are led to inquire whether there exists in the universe any matter from which planetary bodies could be formed, and how far their formation from such matter can be explained by the operation of known material laws.