64 But what is worse is the claim, not only vain but false, irreverent and dangerous, to submit to research, experiment and conclusions of a purely natural and profane order, those matters of education which belong to the supernatural order; as for example questions of priestly or religious vocation, and in general the secret workings of grace which indeed elevate the natural powers, but are infinitely superior to them, and may nowise be subjected to physical laws, for "the Spirit breatheth where He will."
Source: Divini Illius Magistri (Vatican.va)