Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that the Old Law contains no moral precepts. For the Old Law is distinct from the law of nature, as stated above (Question 91, Articles 4,5; Question 98, Article 5). But the moral precepts belong to the law of nature. Therefore they do not belong to the Old Law.

Objection 2: Further, the Divine Law should have come to man's assistance where human reason fails him: as is evident in regard to things that are of faith, which are above reason. But man's reason seems to suffice for the moral precepts. Therefore the moral precepts do not belong to the Old Law, which is a Divine law.

Objection 3: Further, the Old Law is said to be "the letter that killeth" (2 Cor. 3:6). But the moral precepts do not kill, but quicken, according to Ps. 118:93: "Thy justifications I will never forget, for by them Thou hast given me life." Therefore the moral precepts do not belong to the Old Law.

On the contrary, It is written (Ecclus. 17:9): "Moreover, He gave them discipline and the law of life for an inheritance." Now discipline belongs to morals; for this gloss on Heb. 12:11: "Now all chastisement ," etc., says: "Discipline is an exercise in morals by means of difficulties." Therefore the Law which was given by God comprised moral precepts.

I answer that, The Old Law contained some moral precepts; as is evident from Ex. 20:13,15: "Thou shalt not kill, Thou shalt not steal." This was reasonable: because, just as the principal intention of human law is to created friendship between man and man; so the chief intention of the Divine law is to establish man in friendship with God. Now since likeness is the reason of love, according to Ecclus. 13:19: "Every beast loveth its like"; there cannot possibly be any friendship of man to God, Who is supremely good, unless man become good: wherefore it is written (Lev. 19:2; 11:45): "You shall be holy, for I am holy." But the goodness of man is virtue, which "makes its possessor good" (Ethic. ii, 6). Therefore it was necessary for the Old Law to include precepts about acts of virtue: and these are the moral precepts of the Law.

Reply to Objection 1: The Old Law is distinct from the natural law, not as being altogether different from it, but as something added thereto. For just as grace presupposes nature, so must the Divine law presuppose the natural law.

Reply to Objection 2: It was fitting that the Divine law should come to man's assistance not only in those things for which reason is insufficient, but also in those things in which human reason may happen to be impeded. Now human reason could not go astray in the abstract, as to the universal principles of the natural law; but through being habituated to sin, it became obscured in the point of things to be done in detail. But with regard to the other moral precepts, which are like conclusions drawn from the universal principles of the natural law, the reason of many men went astray, to the extend of judging to be lawful, things that are evil in themselves. Hence there was need for the authority of the Divine law to rescue man from both these defects. Thus among the articles of faith not only are those things set forth to which reason cannot reach, such as the Trinity of the Godhead; but also those to which right reason can attain, such as the Unity of the Godhead; in order to remove the manifold errors to which reason is liable.

Reply to Objection 3: As Augustine proves (De Spiritu et Litera xiv), even the letter of the law is said to be the occasion of death, as to the moral precepts; in so far as, to wit, it prescribes what is good, without furnishing the aid of grace for its fulfilment.

Articulus 2

Argumentum 1

Ad secundum sic proceditur. Videtur quod lex vetus non contineat praecepta moralia.

Lex enim vetus distinguitur a lege naturae, ut supra habitum est.

Sed praecepta moralia pertinent ad legem naturae.

Ergo non pertinent ad legem veterem.

Argumentum 2

Praeterea, ibi subvenire debuit homini lex divina, ubi deficit ratio humana, sicut patet in his quae ad fidem pertinent, quae sunt supra rationem. Sed ad praecepta moralia ratio hominis sufficere videtur. Ergo praecepta moralia non sunt de lege veteri, quae est lex divina.

Argumentum 3

Praeterea, lex vetus dicitur littera occidens, ut patet II ad Cor. III.

Sed praecepta moralia non occidunt, sed vivificant; secundum illud Psalmi CXVIII, in aeternum non obliviscar iustificationes tuas, quia in ipsis vivificasti me.

Ergo praecepta moralia non pertinent ad veterem legem.

Sed Contra

Sed contra est quod dicitur Eccli. XVII, addidit illis disciplinam, et legem vitae haereditavit eos.

Disciplina autem pertinet ad mores, dicit enim Glossa ad Heb. XII, super illud, omnis disciplina etc., disciplina est eruditio morum per difficilia.

Ergo lex a deo data, praecepta moralia continebat.

Corpus

Respondeo dicendum quod lex vetus continebat praecepta quaedam moralia, ut patet Exod. XX, non occides, non furtum facies.

Et hoc rationabiliter. Nam sicut intentio principalis legis humanae est ut faciat amicitiam hominum ad invicem; ita intentio legis divinae est ut constituat principaliter amicitiam hominis ad deum. Cum autem similitudo sit ratio amoris, secundum illud Eccli. XIII, omne animal diligit simile sibi; impossibile est esse amicitiam hominis ad deum, qui est optimus, nisi homines boni efficiantur, unde dicitur Levit. XIX, sancti eritis, quoniam ego sanctus sum.

Bonitas autem hominis est virtus, quae facit bonum habentem.

Et ideo oportuit praecepta legis veteris etiam de actibus virtutum dari. Et haec sunt moralia legis praecepta.

Ad 1

Ad primum ergo dicendum quod lex vetus distinguitur a lege naturae non tanquam ab ea omnino aliena, sed tanquam aliquid ei superaddens. Sicut enim gratia praesupponit naturam, ita oportet quod lex divina praesupponat legem naturalem.

Ad 2

Ad secundum dicendum quod legi divinae conveniens erat ut non solum provideret homini in his ad quae ratio non potest, sed etiam in his circa quae contingit rationem hominis impediri. Ratio autem hominis circa praecepta moralia, quantum ad ipsa communissima praecepta legis naturae, non poterat errare in universali, sed tamen, propter consuetudinem peccandi, obscurabatur in particularibus agendis.

Circa alia vero praecepta moralia, quae sunt quasi conclusiones deductae ex communibus principiis legis naturae, multorum ratio oberrabat, ita ut quaedam quae secundum se sunt mala, ratio multorum licita iudicaret. Unde oportuit contra utrumque defectum homini subveniri per auctoritatem legis divinae. Sicut etiam inter credenda nobis proponuntur non solum ea ad quae ratio attingere non potest, ut deum esse trinum; sed etiam ea ad quae ratio recta pertingere potest, ut deum esse unum; ad excludendum rationis humanae errorem, qui accidebat in multis.

Ad 3

Ad tertium dicendum quod, sicut Augustinus probat in libro de spiritu et littera, etiam littera legis quantum ad praecepta moralia, occidere dicitur occasionaliter, inquantum scilicet praecipit quod bonum est, non praebens auxilium gratiae ad implendum.