"In the _theologic_ state, the human mind, directing its researches to the intimate nature of things, the first causes and the final causes of all those effects which arrest its attention, in a word, towards an absolute knowledge of things, represents to itself the phenomena as produced by the direct and continuous action of supernatural agents, more or less numerous, whose arbitrary intervention explains all the apparent anomalies of the universe.
"In the _metaphysic_ state, which is, in its essence, a modification of the former, the supernatural agents are displaced by abstract forces, veritable entities (personified abstractions) inherent in things, and conceived as capable of engendering by themselves all the observed phenomena--whose explanation, thenceforth, consists in assigning to each its corresponding entity.
"At last, in the _positive_ state the human mind, recognizing the impossibility of obtaining absolute notions, renounces the search after the origin and destination of the universe, and the knowledge of the intimate causes of phenomena, to attach itself exclusively to the discovery, by the combined efforts of ratiocination and observation, of their effective laws; that is to say, their invariable relations of succession and of similitude. The explanation of things, reduced now to its real terms, becomes nothing more than the connexion established between the various individual phenomena and certain general facts, the number of which the progress of science tends continually to diminish.
"The _theologic_ system has reached the highest state of perfection of which it is susceptible, when it has substituted the providential action of one only being for the capricious agency of the numerous independent divinities who had previously been imagined. In like manner, the last term of the _metaphysic_ system consists in conceiving, instead of the different special entities, one great general entity, _nature_, considered as the only source of all phenomena. The perfection of the _positive_ system, towards which it unceasingly tends, though it is not probable it can ever attain to it, would be the ability to represent all observable phenomena as particular cases of some one general fact; such, for instance, as that of gravitation."--Vol. I. p. 5.