"Free from all uncleanness, perfect and altogether without spot."
— Denis (Pseudo-Dionysius), On the Divine Names, Chapter 12
"In these words three degrees of cleanness are described which are requisite for sanctity. And the first is the freedom from all uncleanness. Now freedom is the opposite of slavery. But the slave of uncleanness is he who is completely conquered by uncleanness and subject to it. The first grade of purity then is that one should be delivered from the slavery of impurity. Now the second degree is that the purity should be perfect, for the perfect is that to which nothing is lacking. It happens at times that one is not subject to uncleanness, but there is wanting to him something of purity, in so far as he is troubled by passions of uncleanness; and when these are taken away there is perfect purity. The third degree of purity is that one should be altogether without spot. For that is said to be spotted which is not stained by anything intrinsic, but by something extrinsic. One will, then, be altogether without stain when not only in himself he has purity, but also there is nothing without that can draw him to impurity. And in these three degrees the perfect measure of holiness consists."
— St. Thomas Aquinas, Commentary on the Book On the Divine Names of Blessed Denys, cap. 12, lect. 1)