Abstract
After pointing out a meaning difference between "that which is possible not to be at some time is not" and "that which is possible not to be exists for only a finite time", we consider the assumptions necessary in a Thomistic context to derive the conclusion that if everything is contingent then at one time nothing was in existence. The needed key is in limiting the amount of matter which has ever existed, or, since "matter" is not a count-noun, that some 'basic' particulars are finite in number; i.e., particulars which must exist if any physical particulars are to exist. (Though it is not essential to the argument, it is convenient and probably not far off historically to regard "things which are possible not to be" as physical objects.) Given some other assumptions it is then shown the desired conclusion will follow in both a "Genesis" and a "Doomsday" version. We then try to match the argument developed with the Thomistic corpus.