Note 254 — Chapter XX · (continued 2)

M. Cousin has translated and republished two works of Descartes, which had only appeared in Opera Posthuma Cartesii, Amsterdam, 1701. Their authenticity, from external and intrinsic proofs, is out of question. One of these is that mentioned in the text; entitled “Rules for the Direction of the Understanding;” which, though logical in its subject, takes most of its illustrations from mathematics. The other is a dialogue, left imperfect, in which he sustains the metaphysical principles of his philosophy. Of these two little tracts, their editor has said, that “they equal in vigour and perhaps surpass in arrangement the Meditations and Discourse on Method. We see in these more unequivocally the main object of Descartes, and the spirit of the revolution which has created modern philosophy, and placed in the understanding itself the principle of all certainty, the point of departure for all legitimate inquiry. They might seem written but yesterday, and for the present age.” Vol. xi. preface, p. 1. I may add to this, that I consider the Rules for the direction of the Understanding as one of the best works on logic (in the enlarged sense) which I have ever read; more practically useful, perhaps, to young students than the Novum Organum; and though, as I have said, his illustrations are chiefly mathematical, most of his rules are applicable to the general discipline of the reasoning powers. It occupies little more than one hundred pages, and I think that I am doing a service in recommending it. Many of the rules will, of course, be found in later books; some possibly in earlier. This tract, as well as the dialogue which follows it, is incomplete, a portion being probably lost.