The Doctor and Student (1518)
Christopher St. Germain
What sinderesis is
Sinderesis is a natural power of the soul, set in the highest part thereof, moving and stirring it to good and abhorring evil. And therefore sinderesis never sinneth nor erreth. And this sinderesis our Lord put in man, to the intent that the order of things should be observed. For, after St. Dionyse, the wisdom of God joined the beginning of the second things to the last of the first things: for angel is of a nature to understand without searching of reason, and to that nature man is joined by sinderesis, the which sinderesis may not wholly be extincted neither in man ne yet in damned souls. But nevertheless, as to the use and exercise thereof, it may be let for a time, either through the darkness of ignorance, or for undiscreet delectation, or for the hardness of obstinacy. First by the darkness of ignorance, sinderesis may be let that it shall not murmur against evil, because he believeth evil to be good, as it is in heretics, the which, when they die for the wickedness of their error, believe they die for the very truth of their faith. And by undiscreet delectation sinderesis is sometime so overlaid, that remorse or grudge of conscience for that time can have no place. For the hardness of obstinacy sinderesis is also let, that it may not stir to goodness, as it is in damned souls, that be so obstinate in evil, that they may never be inclined to good. And though sinderesis may be said to that point extinct in damned souls, yet it may not be said that it is fully extinct to all intents. For they alway murmur against the evil of the pain that they suffer for sin, and so it may not be said that it is universally, and to all intents, and to all times extinct. And this sinderesis is the beginning of all things that may be learned by speculation or study,. and ministreth the general grounds and principles thereof; and also of all things that are to be done by man. An example of such things as may be learned by speculation appeareth thus: sinderesis saith that every whole thing is more than any one part of the same thing, and that is a sure ground that never faileth. And an example of things that are to be done, or not to be done: as where sinderesis saith no evil is to be done, but that goodness is to be done and followed, and evil to be fled, and such other.
And therefore sinderesis is called by some men the law of reason, for it ministreth the principles of the law of reason, the which be in every man by nature, in that he is a reasonable creature.