And, that we may see the limits of our operations, it is to be known that those alone are our operations which are subject to Reason and to Will; for, if in us there is the digestive operation, that is not human, but natural.

And it is to be known that our Reason is ordained to four operations, separately to be considered; for those are operations which Reason only considers and does not produce, neither can produce, any one of them, such as are the Natural facts and the Supernatural and the Mathematics.

And those are operations which it considers and does in its own proper act which are called rational, such as are the arts of speech.

And those are operations which it considers and does in material beyond itself, such as are the Mechanical Arts.

And all these operations, although the considering them is subject to our will, they in their essential form are not subject to our will; for although we might will that heavy things should mount upwards naturally, they would not be able to ascend; and although we might will that the syllogism with false premisses should conclude with demonstration of the Truth, it could not so conclude; and although we might will that the house should stand as firmly when leaning forward as when upright, it could not be; since of those operations we are not properly the factors, we are their discoverers; Another ordained them and made them, the great Maker, who alone can Will and Do All--God.
There also are operations which our Reason considers and which lie in the act of the Will, such as to offend and to rejoice; such as to stand firm in the battle and to fly from it; such as to be chaste and to be lewd; these are entirely subject to our will, and therefore we are called from them good and evil, because such acts are entirely our own; for so far as our will can obtain power, so far do our operations extend.