 Leibniz’s cosmological argument (Leibniz 1697 [PE]: 149–55; 1714 [PP]: 646, [PE]: 218–19) does not assume or attempt to establish that the world, the collection of all actual contingent beings, has a beginning in time, and in this respect it more closely resembles Avicenna’s argument than al-Ghazali’s. Leibniz argues as follows: suppose that in fact the world has no beginning in time, and that each being in the world has an explanation in some previously existing being(s). Two demands for explanation might still arise: Why is there a world at all rather than none? and: Why does this world exist and not some other world? Neither explanation can be provided by appealing solely to entities within the world (or within time). Leibniz’s conclusion is that there must be a being that is not merely hypothetically, but absolutely necessary, and whose own explanation is contained within itself. This being is God. (A similar cosmological argument is advanced around the same time by Samuel Clarke (1705), see also the entry on  Samuel Clarke).