This or that actual motion of this individual will, not being determinately contained in its cause, since "will-force" is not "determined to any fixed mode of action," how can God, by any knowledge of causes, gain cognisance of this particular motion of free-will as actually taking place? By "a causal influence over the motions of the will," says St Thomas. The discussion of this obscure "causal influence" made the strife of Thomist and Molinist in the seventeenth century.

Of God and His Creatures: 1.68