 Because being and unity are not univocal, we cannot just straightforwardly investigate their attributes and causes, but once they have been analyzed into their different senses, we can investigate the attributes and causes of each sense of being or unity in the same way that any other science investigates the attributes and causes of some given genus. A given effect, say substantial being, may have different kinds of causes (for instance, both a formal cause and a material cause), and these different kinds of causes may not all converge on a first principle which is a cause in all these ways at once (there will not be a single first principle that is both a formal and a material cause). Some chains of causes may proceed upwards ad infinitum without reaching a first principle (like the chain of my ancestors, if the world and species within it are eternal); and chains of causes of some kind may lead to many first causes which have no further causes of that kind, rather than to a single first cause (each animal has a soul as a first formal cause which has no higher formal cause, but there will be as many such souls, not a single soul which is a first formal cause of all animals). Nonetheless, Fârâbî claims that there is a single first cause of all beings, which does not itself have a cause of any kind; if so, such a thing would deserve the name  “God”.[13]  If the science can show that there is such a single first principle, the science would then try to deduce what this principle must be like in order to be a cause of all beings, and in order not to have any further cause itself, and would then try to deduce how it must acts in order to cause the existence of other things, some directly and others indirectly. Here in On the Aims Fârâbî says that Aristotle does all these things in Metaphysics XII: