This is truly a magnificent argument. -- In these idealist days, there is no difficulty in bringing any theist to avow that things could not be at all, if they dropped out of the thought of the Supreme Mind. But God's mere thinking of them is not enough to raise them out of the order of pure possibilities, and transfer them into the region of actual being. To give them actuality, God must will them; and to keep them in existence He must will them continually. Cf. B. I, Chapp. LIII, LIV, LXXXI.
Of God and His Creatures: 3.65