Philosophy, in the highest acceptation of the term, is the search after a solution for the universal problem the terms of which may be stated as follows: Experience reveals to us that the world is composed of manifold and diverse beings; and, to come at once to the great division, there are in the world bodies which we are forced to suppose inert, and minds which we feel to be intelligent and free. The universe is made up of manifold existences; this is quite evident, and a matter of experience. Reason on the other hand forces us to seek for unity. To comprehend, is to reduce phenomena to their laws, to connect effects with their causes, consequences with their principles; it is to be always introducing unity into the diversity. All development of science would be at once arrested, if the mind could content itself with merely taking account of facts in the state of dispersion in which they are presented by experience. Each particular science gathers up a multitude of facts into a small number of formulae; and, above and beyond particular sciences, reason searches for the connection of all things with one single cause. To determine the relation of all particular existences with one existence which is their common cause; such is the universal problem. This problem has been very well expressed by Pythagoras in a celebrated formula, that of the _Uni-multiple_. In order to understand the universe, we must rise to a unity which may account for the multiplicity of things and for their harmony, which is unity itself maintained in diversity.