The attribute of divine aseity is defined. God alone is self-existent and therefore uncreated, the sole ultimate reality. Platonism's challenge to the doctrine of divine aseity is introduced. The distinction between abstract and concrete objects is expounded. A distinction between heavyweight and lightweight Platonism is drawn and illustrated from the work of Bob Hale and Crispin Wright, Michael Dummett, and John Burgess and Gideon Rosen. It is explained that only heavyweight Platonism challenges divine aseity and so will be the subject of discussion.