As regards things, on which Descartes now directs his attention, the other side to these eternal verities, the universal determinations of things are substance, permanence, order, &c.[181] He then gives definitions of these thoughts, just as Aristotle draws up a list of the categories. But although Descartes laid it down formerly as essential that no hypotheses must be made, yet now he takes the conceptions, and passes on to them as something found within our consciousness. He defines substance thus: “By substance I understand none other than a thing (_rem_) which requires no other something for existence; and there is only one thing, namely God, which can be regarded as such a substance requiring no other thing.” This is what Spinoza says; we may say that it is likewise the true definition, the unity of Notion and reality: “All other” (things) “can only exist by means of a concurrence (_concursus_) of God”; what we still call substance outside of God thus does not exist for itself, does not have its existence in the Notion itself. That is then called the system of assistance (_systema assistentiæ_) which is, however, transcendental. God is the absolute uniter of Notion and actuality; other things, finite things which have a limit and stand in dependence, require something else. “Hence if we likewise call other things substances, this expression is not applicable both to them and to God _univoce_, as is said in the schools; that is to say no definite significance can be given to this word which would equally apply both to God and to the creatures.”[182] “But I do not recognize more than two sorts of things; the one is that of thinking things, and the other that of things which relate to what is extended.” Thought, the Notion, the spiritual, the self-conscious, is what is at home with itself, and its opposite is contained in what is extended, spatial, separated, not at home with itself nor free. This is the real distinction (_distinctio realis_) of substances: “The one substance can be clearly and definitely comprehended without the other. But the corporeal and the thinking and creating substance can be comprehended under this common notion, for the reason that they are things which require God’s support alone in order to exist.” They are universal; other finite things require other things as conditions essential to their existence. But extended substance, the kingdom of nature, and spiritual substance, do not require one another.[183] They may be called substances, because each of them constitutes an entire range or sphere, an independent totality. But because, Spinoza concluded, each side, the kingdom of thought as well as nature, is one complete system within itself, they are likewise in themselves, that is absolutely, identical as God, the absolute substance; for thinking spirit this implicit is thus God, or their differences are ideal.