 In the medieval period, the discussion embraces not only Christian but also Jewish and Islamic thinkers. In keeping with the sharp line drawn between the Creator and creation, Aquinas and the Jewish thinker Moses Maimonides (1131–1204) (who greatly influenced Aquinas) argue that God’s timeless eternity ought to be understood primarily in negative terms. For Aquinas, God’s timeless eternity is unending, lacking both beginning and end, and an instantaneous whole lacking succession. It is a correlate of divine simplicity (see the SEP entry on  divine simplicity),  and it is incapable of being defined or fully grasped by a creature. For Aquinas too, timeless eternity constitutes part of the “grammar” of talking about God. Since God is timelessly eternal it does not make any sense to ask how many years God has existed, or whether he is growing old, or what will he be doing later on in the year.