Thomas Aquinas

“ We indeed from being sinners are made holy: so that our sanctification is a cleansing from sin. Whereas Christ, as man, was made holy, because He was not always thus sanctified by grace: yet He was not made holy from being a sinner, because He never sinned ”

“ Therefore it seems that the use of free-will, which Christ as man had in the first instant of His conception, was not meritorious.
Objection 3: Further, that which a man has once merited he makes, in a way, his own: consequently it seems that he cannot merit the same thing again: for no one merits what is already his. If, therefore, Christ merited in the first instant of His conception, it follows that afterwards He merited nothing. But this is evidently untrue. Therefore Christ did not merit in the first instant of His conception. ”

“ To be sanctified is to be made holy. Now something is made not only from its contrary, but also from that which is opposite to it, either by negation or by privation: thus white is made either from black or from not-white. ”