It is strange that any one, after such a warning, should rely implicitly on the evidence _à priori_ of such propositions as these, that matter cannot think; that space, or extension, is infinite; that nothing can be made out of nothing (_ex nihilo nihil fit_). Whether these propositions are true or not this is not the place to determine, nor even whether the questions are soluble by the human faculties. But such doctrines are no more self-evident truths, than the ancient maxim that a thing cannot act where it is not, which probably is not now believed by any educated person in Europe.[7] Matter cannot think; why? because we _cannot conceive_ thought to be annexed to any arrangement of material particles. Space is infinite, because having never known any part of it which had not other parts beyond it, we _cannot conceive_ an absolute termination. _Ex nihilo nihil fit_, because having never known any physical product without a pre-existing physical material, we _cannot_, or think we cannot, _imagine_ a creation out of nothing. But these things may in themselves be as conceivable as gravitation without an intervening medium, which Newton thought too great an absurdity for any person of a competent faculty of philosophical thinking to admit: and even supposing them not conceivable, this, for aught we know, may be merely one of the limitations of our very limited minds, and not in nature at all. No writer has more directly identified himself with the fallacy now under consideration, or has embodied it in more distinct terms, than Leibnitz. In his view, unless a thing was not merely conceivable, but even explainable, it could not exist in nature. All _natural_ phenomena, according to him, must be susceptible of being accounted for _à priori_. The only facts of which no explanation could be given but the will of God, were miracles properly so called. "Je reconnais," says he,[8] "qu'il n'est pas permis de nier ce qu'on n'entend pas; mais j'ajoute qu'on a droit de nier (au moins dans l'ordre naturel) ce qui absolument n'est point intelligible ni explicable. Je soutiens aussi ... qu'enfin la conception des créatures n'est pas la mesure du pouvoir de Dieu, mais que leur conceptivité, ou force de concevoir, est la mesure du pouvoir de la nature, tout ce qui est conforme à l'ordre naturel pouvant être conçu ou entendu par quelque créature."