From: The Catholic Encyclopedia
Synderesis, or more correctly synteresis, is a term used by the Scholastic theologians to signify the habitual knowledge of the universal practical principles of moral action. The reasoning process in the field of speculative science presupposes certain fundamental axioms on which all science rests. Such are the principle of contradiction, "a thing cannot be and not be at the same time," and self-evident truths like "the whole is greater than its part". These are the first principles of the speculative intellect. In the field of moral conduct there are similar first principles of action, such as: "evil must be avoided, good done"; "Do not to others what you would not wish to be done to yourself"; "Parents should be honoured"; "We should live temperately and act justly". Such as these are self-evident truths in the field of moral conduct which any sane person will admit if he understands them. According to the Scholastics, the readiness with which such moral truths are apprehended by the practical intellect is due to the natural habit impressed on the cognitive faculty which they call synderesis. While conscience is a dictate of the practical reason deciding that any particular action is right or wrong, synderesis is a dictate of the same practical reason which has for its object the first general principles of moral action.
The Catholic Encyclopedia, Volume XIV. Published 1912. New York: Robert Appleton Company. Nihil Obstat, July 1, 1912. Remy Lafort, S.T.D., Censor. Imprimatur. +John Cardinal Farley, Archbishop of New York
1 ¶ And seeing the multitudes, he went up into a mountain, and when he was set down, his disciples came unto him.
2 And opening his mouth he taught them, saying:
3 ¶ Blessed are the poor in spirit: for theirs is the kingdom of heaven.
4 Blessed are the meek: for they shall possess the land.
5 Blessed are they that mourn: for they shall be comforted.
6 Blessed are they that hunger and thirst after justice: for they shall have their fill.
7 Blessed are the merciful: for they shall obtain mercy.
8 Blessed are the clean of heart: they shall see God.
9 Blessed are the peacemakers: for they shall be called the children of God.
10 Blessed are they that suffer persecution for justice' sake: for theirs is the kingdom of heaven.
11 Blessed are ye when they shall revile you, andpersecute you, and speak all that is evilagainst you, untruly, for my sake:
12 Be glad and rejoice for your reward is very great in heaven. For so they persecuted the prophets that were before you.
13 ¶ You are the salt of the earth. But if the salt lose its savour, wherewith shall it be salted? It is good for nothing anymore but to be cast out, and to be trodden on by men.
14 You are the light of the world. A city seated on a mountain cannot be hid.
15 Neither do men light a candle and put it under a bushel, but upon a candlestick, that it may shine to all that are in the house.
16 So let your light shine before men, that they may see your good works, and glorify your Father who is in heaven.
17 ¶ Do not think that I am come to destroy the law, or the prophets. I am not come to destroy, but to fulfil.
18 For amen I say unto you, till heaven and earth pass, one jot, or one tittle shall not pass of the law, till all be fulfilled.
3 Being manifested, that you are the epistle of Christ, ministered by us, and written: not with ink but with the Spirit of the living God: not in tables of stone but in the fleshly tables of the heart. (DRV)
1 ¶ And the Lord spoke all these words:
2 I am the Lord thy God, who brought thee out of the land of Egypt, out of the house of bondage.
3 Thou shalt not have strange gods before me.
4 Thou shalt not make to thyself a graven thing, nor the likeness of any thing that is in heaven above, or in the earth beneath, nor of those things that are in the waters under the earth.
5 Thou shalt not adore them, nor serve them: I am the Lord thy God, mighty, jealous, visiting the iniquity of the fathers upon the children, unto the third and fourth generation of them that hate me:
6 And shewing mercy unto thousands to them that love me, and keep my commandments.
7 Thou shalt not take the name of the Lord thy God in vain: for the Lord will not hold him guiltless that shall take the name of the Lord his God in vain.
8 Remember that thou keep holy the sabbath day.
9 Six days shalt thou labour, and shalt do all thy works.
10 But on the seventh day is the sabbath of the Lord thy God: thou shalt do no work on it, thou nor thy son, nor thy daughter, nor thy manservant, northy maidservant, nor thy beast, nor the stranger that is within thy gates.
11 For in six days the Lord made heaven and earth, and the sea, and all things that are in them, and rested on the seventh day: therefore the Lord blessed the seventh day, and sanctified it.
12 ¶ Honour thy father and thy mother, that thou mayst be long lived upon the land which the Lord thy God will give thee.
13 Thou shalt not kill.
14 Thou shalt not commit adultery.
15 Thou shalt not steal.
16 Thou shalt not bear false witness against thy neighbour.
17 Thou shalt not covet thy neighbour's house; neither shalt thou desire his wife, nor his servant, nor his handmaid, nor his ox, nor his ass, nor any thing that is his.