We should, perhaps, beg your pardon for the austerity of this lecture. But philosophical questions must be treated philosophically: it does not belong to us to change their character. On other subjects, another language. Psychology has its own language, the entire merit of which is a severe precision, as the highest law of psychology itself is the shunning of every hypothesis, and an inviolable respect for facts. This law we have religiously followed. While investigating the origin of universal and necessary principles, we have especially endeavored not to destroy the thing to be explained by a systematic explanation. Universal and necessary principles have come forth in their integrity from our analysis. We have given the history of the different forms which they successively assume, and we have shown, that in all these changes they remain the same, and of the same authority, whether they enter spontaneously and involuntarily into exercise, and apply themselves to particular and determinate objects, or reflection turns them back upon themselves in order to interrogate them in regard to their nature, or abstraction makes them appear under the form in which their universality and their necessity are manifest. Their certainty is the same under all their forms, in all their applications; it has neither generation nor origin; it is not born such or such a day, and it does not increase with time, for it knows no degrees. We have not commenced by believing a little in the principle of causality, of substances, of time, of space, of the infinite, etc., then believing a little more, then believing wholly. These principles have been, from the beginning, what they will be in the end, all-powerful, necessary, irresistible. The conviction which they give is always absolute, only it is not always accompanied by a clear consciousness. Leibnitz himself has no more confidence in the principle of causality, and even in his favorite principle of sufficient reason, than the most ignorant of men; but the latter applies these principles without reflecting on their power, by which he is unconsciously governed, whilst Leibnitz is astonished at their power, studies it, and for all explanation, refers it to the human mind, and to the nature of things, that is to say, he elevates, to borrow the fine expression of M. Royer-Collard,[36] the ignorance of the mass of men to its highest source. Such is, thank heaven, the only difference that separates the peasant from the philosopher, in regard to those great principles of every kind which, in one way or another, discover to men the same truths indispensable to their physical, intellectual, and moral existence, and, in their ephemeral life, on the circumscribed point of space and time where fortune has thrown them, reveal to them something of the universal, the necessary, and the infinite. FOOTNOTES: [25] First Series, vol. iv., lectures 1, 2, and 3. [26] _Ibid._, vol. iv., etc. [27] _Ibid._, vol. v., lecture 8.