 Here Descartes might seem to be offering a theory of possibility according to which what it means for something to be possible is just for it to be  conceivable.[34]  However, this cannot be Descartes’ view. Descartes holds that whatever we clearly and distinctly perceive is true and that truth is “the conformity of thought with its object” (“To Mersenne, 16 October 1639,” AT 2:597, CSMK 139). If a possibility that we are considering is clearly and distinctly perceived, then our clear and distinct perception conforms to reality, and the possibility that we are conceiving is not merely conceptual. Instead, there is also an object to which the clear and distinct perception conforms – the sort of thing posited by commentators who argue that Descartes holds that God’s creation consists not only of actuals but of unactualized possibles. Thus, for any possibility of which we have a conception, if there is no object to which that conception conforms – that is, if the possibility exists only in thought – the possibility is not clearly and distinctly perceived. Possibilities which exist only in thought are not part of Descartes’ ontology and so on Descartes’ view are not possibilities at all. Descartes’ remarks to Mersenne actually bear this out. He is indeed considering the view of possibility as conceivability, but in doing so he is merely acknowledging what “everyone commonly means” by ‘possible’. Descartes sometimes speaks of the possible as clearly and distinctly perceived. It is on these passages that any interpretation of Descartes’ views on possibility must be built.