(e) according to the progress of a sin, there are three stages: first, it is a sin of the heart when it exists only in the mind, as when one entertains a wish for revenge; secondly, it is a sin of the mouth, when it is manifested in words, as when one uses contumelious language; thirdly, it is a sin of work when it is carried out in act, as when one strikes another in the face; (f) according to the manner in which they deviate from the golden mean, sins are either of excess (e.g., extravagance) or of defect (e.g., miserliness); (g) according to the manner in which its guilt is contracted, sin is either original (i.e., the loss of grace inherited from Adam) or actual (i.e., the stain derived from one’s own wrongdoing; sec 272 sqq.). 169. Mortal Sin.--A sin is mortal or deadly, when by it a person turns away from God, his Last End, and prefers to Him some created good, thereby incurring the debt of eternal punishment. 170. The first condition necessary in order that a sin may be judged mortal is that the matter of the sin be grave, either in itself or in the opinion of him who commits it; it must include turning away from God and the substitution of some created good as the Last End. 171. The matter of a sin is known to be grave: (a) when the law of God or of the Church declares that it is seriously displeasing to God, or that it will separate one from His favor or rewards; (b) when right reason shows that it does great injury to the rights of God, of society, of one’s neighbor, or of oneself. 172. The matter of a sin is grave in two ways. (a) It is grave from the character of the act and without exception, when the good which is injured is infinite, or is a finite good of greatest importance and indivisible, Thus, heresy, despair, and simony against divine law are always serious, because they offend against an infinite good; while murder, though it injures only a finite good, is nevertheless always grave matter because earthly life is of highest importance among finite goods, and if taken away is taken entirely. (b) The matter of a sin is grave from the character of the act but with exceptions, when the good that is injured is of grave importance, but finite and divisible. Thus, the worship we give to God is finite and admits of more and less; and hence a sin against worship, though serious from the nature of the offence, may be slight on account of the smallness of the irreverence. Similarly, though theft injures a grave right, it is not grave matter when the amount stolen is small. 173. The second condition required that a sin be mortal is that there be full advertence to the grave malice of the act, for one cannot be said to separate oneself from God unless one has made the same amount of deliberation that is required for any temporal affair of great moment.