…the Lord requires as the very first step in the way of the Spirit that birth from the Spirit contribute to man’s freedom of choice rather than take it away. For there would be a great loss in merit if the Spirit determined the will and worked in it by violence rather than by breathing and actuating its inclinations. For this reason the Apostle wrote that the spirits of the prophets are under the control of the prophets. This is interpreted by St. Thomas to mean that as far as the use of the power of announcing prophecies is concerned the spirits are subject to the will of the prophet and are not like delirious ravings.
The gifts of the Holy Ghost, therefore, are given to the soul after the manner of habits, so that in a rational and voluntary way the soul may be moved to those works to which it is directed by the Spirit. Thus, those who are conducted by the Spirit are moved not as slaves but as free men, willingly and voluntarily, since the principles which move them, though derived from the Spirit, are inherent in their very souls. They are impelled to operations which by their character and measure exceed all ordinary human standards.
-John of St. Thomas (John Poinsot), The Gifts of the Holy Ghost, trans. Dominic Hughes (New York: Sheed and Ward, 1951), p. 28; cited in Jacques Maritain, Moral Philosophy: An historical and critical survey of the great systems (London: Bles, 1964), pp. 438-9, fn. 4