"Such has gradually become, since the time of Bacon, the preponderance of the positive philosophy; it has at present assumed indirectly so great an ascendant over those minds even which have been most estranged from it, that metaphysicians devoted to the study of our intelligence, can no longer hope to delay the fall of their pretended science, but by presenting their doctrines as founded also upon the observation of facts. For this purpose they have, in these later times, attempted to distinguish, by a very singular subtilty, two sorts of observations of equal importance, the one external, the other internal; the last of which is exclusively destined for the study of intellectual phenomena. This is not the place to enter into the special discussion of this sophism. I will limit myself to indicate the principal consideration, which clearly proves that this pretended direct contemplation of the mind by itself, is a pure illusion. "Not a long while ago men imagined they had explained vision by saying that the luminous action of bodies produces on the retina pictures representative of external forms and colours. To this the physiologists [query, the _physiologists_] have objected, with reason, that if it was _as images_ that the luminous impressions acted, there needed another eye within the eye to behold them. Does not a similar objection hold good still more strikingly in the present case? "It is clear, in fact, from an invincible necessity, that the human mind can observe directly all phenomena except its own. For by whom can the observation be made? It is conceivable that, relatively to moral phenomena, man can observe himself in regard to the passions which animate him, from this anatomical reason, that the organs which are the seat of them are distinct from those destined to the function of observation. Though each man has had occasion to make on himself such observations, yet they can never have any great scientific importance; and the best means of knowing the passions will be always to observe them without; [_indeed_!] for every state of passion very energetic--that is to say, precisely those which it would be most essential to examine, are necessarily incompatible with the state of observation. But as to observing in the same manner intellectual phenomena, while they are proceeding, it is manifestly impossible. The thinking individual cannot separate himself in two parts, of which the one shall reason, and the other observe it reasoning. The organ observed and the organ observing being in this case identical, how can observation be carried on?