At length the whole science of man became a confused mass of darkness, falsehood, and contradictions, with here and there a feeble ray of truth, furnished by that Nature, of which he can never entirely divest himself; because, without his perception, his necessities are continually bringing him back to her resources. Let us then, if possible, raise ourselves above these clouds of prepossession! Let us quit the heavy atmosphere in which we are enucleated; let us in a more unsullied medium--in a more elastic current, contemplate the opinions of men, and observe their various systems. Let us learn to distrust a disordered conception; let us take that faithful monitor, experience, for our guide; let us consult Nature, examine her laws, dive into her stores; let us draw from herself, our ideas of the beings she contains; let us recover our senses, which interested error has taught us to suspect; let us consult that reason, which, for the vilest purposes has been so infamously calumniated, so cruelly dishonoured; let us examine with attention the visible world; let us try, if it will not enable us to form a supportable judgment of the invisible territory of the intellectual world: perhaps it may be found there has been no sufficient reason for distinguishing them--that it is not without motives, well worthy our enquiry, that two empires have been separated, which are equally the inheritance of nature. The universe, that vast assemblage of every thing that exists, presents only matter and motion: the whole offers to our contemplation, nothing but an immense, an uninterrupted succession of causes and effects; some of these causes are known to us, because they either strike immediately on our senses, or have been brought under their cognizance, by the examination of long experience; others are unknown to us, because they act upon us by effects, frequently very remote from their primary cause. An immense variety of matter, combined under an infinity of forms, incessantly communicates, unceasingly receives a diversity of impulses. The different qualities of this matter, its innumerable combinations, its various methods of action, which are the necessary consequence of these associations, constitute for man what he calls the ESSENCE of beings: it is from these varied essences that spring the orders, the classes, or the systems, which these beings respectively possess, of which the sum total makes up that which is known by the term _nature_.