12. It seems, therefore, that a single being ought to be defined as _ens indivisum in se_, or a being which includes no division. Unity, then, will depend upon non-distinction. If non-division denote _non-distinction_, there will be real unity; but if it denote _non-separation_ or re-union, we shall only have a fictitious unity. The molecules without extension, of which many suppose matter to be composed, would be really _one_, because there is no distinction in them. Bodies are fictitiously _one_ because their composite parts though united are really distinct. 13. A difficulty may be raised by asking whether a being, indivisible in itself, but not divided from others, would be really _one_, for in case it would not be _one_, it might be inferred that we had unjustly censured the definition of the schoolmen, since whatever wants the second property required by the definition would not be one. We reply, then, a being that includes no distinction in itself, and is not distinguished from others, would indeed be one, but in such a case there would be no _others_, since they cannot be when there is no distinction. In such an hypothesis, there would be only one unity, the unity of pantheism, the _great all_, the absolute in which all things would be identified. 14. We have already said that the unity which is confounded with being, is not the unity which originates number. We here in fact encounter two different conceptions of unity, the one marking only want of distinction, and the other expressing the property of engendering number. But we are not thence to infer that the one which is identified with being is distinct from that which engenders number. All beings, one in themselves, but distinct from each other, no matter what they may be, may be conceived under the idea of number. The number _three_ enters into the august mystery of the Trinity, and we say with all truth that in God there are _three_ persons. 15. It is not necessary that the unity which engenders number should be real; it suffices if it be fictitious. When we take a foot measure for unity, we employ a fictitious unity, since the foot is composed of parts, but the number which results therefrom is, nevertheless, a true number. CHAPTER III. UNITY AND SIMPLICITY. 16. Real unity and simplicity are identical. What is really one has no distinction in itself; nor is it composed of parts, of which it can be said, this _is not_ that. Evidently simplicity requires nothing more; the simple is opposed to the composite, to what is formed of many beings whereof one _is not_ the other. 17. We meet this simplicity in none of the objects of our intuitions, excepting the acts of our own mind; so that even when we know, by discursion, that there are substances really one or simple, we do not see them in themselves.