2. Now the truths of reason are of two kinds: the one kind is of those called the 'Eternal Verities', which are altogether necessary, so that the opposite implies contradiction. Such are the truths whose necessity is logical, metaphysical or geometrical, which one cannot deny without being led into absurdities. There are others which may be called _positive_, because they are the laws which it has pleased God to give to Nature, or because they depend upon those. We learn them either by experience, that is, _a posteriori_, or by reason and _a priori_, that is, by considerations of the fitness of things which have caused their choice. This fitness of things has also its rules and reasons, but it is the free choice of God, and not a geometrical necessity, which causes preference for what is fitting and brings it into existence. Thus one may say that physical necessity is founded on moral necessity, that is, on the wise one's choice which is worthy of his wisdom; and that both of these ought to be distinguished from geometrical necessity. It is this physical necessity that makes order in Nature and lies in the rules of motion and in some other general laws which it pleased God to lay down for things when he gave them being. It is therefore true that God gave such laws not without reason, for he chooses nothing from caprice and as though by chance or in pure indifference; but the general reasons of good and of order, which have prompted him to the choice, may be overcome in some cases by stronger reasons of a superior order.