M. Cousin excels in explaining these numberless philosophical combinations, and in tracing them all back to the four great systems which he has defined; but there is a fact still more important than the variety of these combinations, and which calls itself for explanation. Why did these four essential systems--sensualism, idealism, scepticism, and mysticism, appear from the most ancient times? why have they continued to reproduce themselves always and everywhere, with deductions more or less logical, with greater or less ability, but still fundamentally always and everywhere the same? Why, upon these supreme questions, did the human mind achieve at so early a period, what may be termed, it is true, but essays at a solution, but which essays in some sort have exhausted the mind rather than satisfied it? {129} How is it that these different systems, invented with such promptitude, have never been able either to come to an accord, nor has any one been able to prevail decidedly against another and to cause itself to be received as the truth? Why has philosophy, or, to speak more precisely, why have metaphysics, remained essentially stationary; great at their birth, but destined not to grow: whereas the other sciences--those styled natural sciences--have been essentially progressive: at first feeble, and making in succession conquest after conquest; these they have been able to retain, until they have formed a domain day by day more extended and less contested? The very fact that suggests these questions contains the answer to them. Man has, upon the fundamental subject of metaphysics, a primitive light, rather the heritage and dowry of human nature, than the conquest of human science. {130} The metaphysician appropriates it as a torch to lighten him on his obscure and ill-defined path. He finds in man himself a point of departure at once profound and certain; but his aim is God; that is to say, an aim above his reach. Must we, then, renounce the study of the great questions which form the subject of metaphysics as a vain labour, where the human mind is turning indefinitely in the same circle, incapable not only of attaining the object which it is pursuing, but of making any advance in its pursuit?