There are philosophers who go farther, and teach, not only a general, but an invariable, and inviolable, and necessary uniformity in the action of the laws of nature, holding that every thing is the result of some law or laws, and that exceptions are impossible; but I do not see on what ground of experience or reason they take up this position. Our experience rather is adverse to such a doctrine, for what concrete fact or phenomenon exactly repeats itself? Some abstract conception of it, more perfect than the recurrent phenomenon itself, is necessary, before we are able to say that it has happened even twice, and the variations which accompany the repetition are of the nature of exceptions. The earth, for instance, never moves exactly in the same orbit year by year, but is in perpetual vacillation. It will, indeed, be replied that this arises from the interaction of one law with another, of which the actual orbit is only the accidental issue, that the earth is under the influence of a variety of attractions from cosmical bodies, and that, if it is subject to continual aberrations in its course, these are accounted for accurately or sufficiently by the presence of those extraordinary and variable attractions:—science, then, by its analytical processes sets right the _primâ facie_ confusion. Of course; still let us not by our words imply that we are appealing to experience, when really we are only accounting, and that by hypothesis, for the absence of experience. The confusion is a fact, the reasoning processes are not facts. The extraordinary attractions assigned to account for our experience of that confusion are not themselves experienced phenomenal facts, but more or less probable hypotheses, argued out by means of an assumed analogy between the cosmical bodies to which those attractions are referred and falling bodies on the earth. I say “assumed,” because that analogy (in other words, the unfailing uniformity of nature) is the very point which has to be proved. It is true, that we can make experiment of the law of attraction in the case of bodies on the earth; but, I repeat, to assume from analogy that, as stones do fall to the earth, so Jupiter, if let alone, would fall upon the earth and the earth upon Jupiter, and with certain peculiarities of velocity on either side, is to have recourse to an explanation which is not necessarily valid, unless nature is necessarily uniform. Nor, indeed, has it yet been proved, nor ought it to be assumed, even that the law of velocity of falling bodies on the earth is invariable in its operation; for that again is only an instance of the general proposition, which is the very thesis in debate. It seems safer then to hold that the order of nature is not necessary, but general in its manifestations.