Observation and reflection ought to convince us, that every thing in Nature is in continual motion--that there is not a single part, however small, that enjoys repose--that Nature acts in all--that she would cease to be Nature if she did not act. Practical knowledge teaches us, that without unceasing motion, nothing could be preserved--nothing could be produced--nothing could act in this Nature. Thus the idea of Nature necessarily includes that of motion. But it will be asked, and not a little triumphantly, from whence did she derive her motion? Our reply is, we know not, neither do they--that _we_ never shall, that _they_ never will. It is a secret hidden from us, concealed from them, by the most impenetrable veil. We also reply, that it is fair to infer, unless they can logically prove to the contrary, that it is in herself, since she is the great whole, out of which nothing can exist. We say this motion is a manner of existence, that flows, necessarily, out of the nature of matter; that matter moves by its own peculiar energies; that its motion is to be attributed to the force which is inherent in itself; that the variety of motion, and the phenomena which result, proceed from the diversity of the properties--of the qualities--of the combinations, which are originally found in the primitive matter, of which Nature is the assemblage. Natural philosophers, for the most part, have regarded as inanimate, or as deprived of the faculty of motion, those bodies which are only moved by the intervention of some agent or exterior cause; they have considered themselves justified in concluding, that the matter which forms these bodies is perfectly inert in its nature. They have not forsaken this error, although they must have observed, that whenever a body is left to itself, or disengaged from those obstructions which oppose themselves to its descent, it has a tendency to fall or to approach the centre of the earth, by a motion uniformly accelerated; they have rather chosen to suppose a visionary exterior cause, of which they themselves had but an imperfect idea, than admit that these bodies held their motion from their own peculiar nature.