 The notion of unexercised eternal powers also faces the difficulty that unexercised powers appear to be powers for future acts and, if genuine, can be exercised in the future.  But how could a timeless being, as God is, exercise at a future time his power to know or will what he in fact does not know or will; indeed, are not such powers described as powers to know or will without beginning? Such an attribution of power to God therefore seems to be empty (frustra).  The problem Grosseteste confronts here is central to anyone who, like him, takes God to be timeless and yet to have powers to do what he does not do, and it is to Grosseteste’s credit that he puts the problem squarely on the table. His solution appeals to the idea that God’s powers to know or will are rational powers, powers that can be exercised in more than one way (the concept of a rational power is drawn from Aristotle).  Thus the power to know that p is the same as the power to not-know that p. But given such a conception of power, if God knows that p, then his power to not-know that p is ipso facto exercised, since it is the very same power as the power to know that p. So there are no unexercised powers in God after all. Thomas Bradwardine noted in criticism of this account that a more plausible requirement on exercisability is that if an agent has a power to know that p and does not know that p, then he can exercise that power by knowing that p.  Grosseteste has no reply to this objection; its answer would require a more thoroughgoing examination of the relation of power to time and change than Grosseteste gives (see Lewis 1996).