Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that it was not necessary for the reparation of the human race that the Word of God should become incarnate. For since the Word of God is perfect God, as has been said (1, Question 4, Articles 1,2), no power was added to Him by the assumption of flesh. Therefore, if the incarnate Word of God restored human nature. He could also have restored it without assuming flesh.

Objection 2: Further, for the restoration of human nature, which had fallen through sin, nothing more is required than that man should satisfy for sin. Now man can satisfy, as it would seem, for sin; for God cannot require from man more than man can do, and since He is more inclined to be merciful than to punish, as He lays the act of sin to man's charge, so He ought to credit him with the contrary act. Therefore it was not necessary for the restoration of human nature that the Word of God should become incarnate.

Objection 3: Further, to revere God pertains especially to man's salvation; hence it is written (Mal. 1:6): "If, then, I be a father, where is my honor? and if I be a master, where is my fear?" But men revere God the more by considering Him as elevated above all, and far beyond man's senses, hence (Ps. 112:4) it is written: "The Lord is high above all nations, and His glory above the heavens"; and farther on: "Who is as the Lord our God?" which pertains to reverence. Therefore it would seem unfitting to man's salvation that God should be made like unto us by assuming flesh.

On the contrary, What frees the human race from perdition is necessary for the salvation of man. But the mystery of the Incarnation is such; according to Jn. 3:16: "God so loved the world as to give His only-begotten Son, that whosoever believeth in Him may not perish, but may have life everlasting." Therefore it was necessary for man's salvation that God should become incarnate.

I answer that, A thing is said to be necessary for a certain end in two ways. First, when the end cannot be without it; as food is necessary for the preservation of human life. Secondly, when the end is attained better and more conveniently, as a horse is necessary for a journey. In the first way it was not necessary that God should become incarnate for the restoration of human nature. For God with His omnipotent power could have restored human nature in many other ways. But in the second way it was necessary that God should become incarnate for the restoration of human nature. Hence Augustine says (De Trin. xii, 10): "We shall also show that other ways were not wanting to God, to Whose power all things are equally subject; but that there was not a more fitting way of healing our misery."

Now this may be viewed with respect to our "furtherance in good." First, with regard to faith, which is made more certain by believing God Himself Who speaks; hence Augustine says (De Civ. Dei xi, 2): "In order that man might journey more trustfully toward the truth, the Truth itself, the Son of God, having assumed human nature, established and founded faith." Secondly, with regard to hope, which is thereby greatly strengthened; hence Augustine says (De Trin. xiii): "Nothing was so necessary for raising our hope as to show us how deeply God loved us. And what could afford us a stronger proof of this than that the Son of God should become a partner with us of human nature?" Thirdly, with regard to charity, which is greatly enkindled by this; hence Augustine says (De Catech. Rudib. iv): "What greater cause is there of the Lord's coming than to show God's love for us?" And he afterwards adds: "If we have been slow to love, at least let us hasten to love in return." Fourthly, with regard to well-doing, in which He set us an example; hence Augustine says in a sermon (xxii de Temp.): "Man who might be seen was not to be followed; but God was to be followed, Who could not be seen. And therefore God was made man, that He Who might be seen by man, and Whom man might follow, might be shown to man." Fifthly, with regard to the full participation of the Divinity, which is the true bliss of man and end of human life; and this is bestowed upon us by Christ's humanity; for Augustine says in a sermon (xiii de Temp.): "Go was made man, that man might be made God."

So also was this useful for our "withdrawal from evil." First, because man is taught by it not to prefer the devil to himself, nor to honor him who is the author of sin; hence Augustine says (De Trin. xiii, 17): "Since human nature is so united to God as to become one person, let not these proud spirits dare to prefer themselves to man, because they have no bodies." Secondly, because we are thereby taught how great is man's dignity, lest we should sully it with sin; hence Augustine says (De Vera Relig. xvi): "God has proved to us how high a place human nature holds amongst creatures, inasmuch as He appeared to men as a true man." And Pope Leo says in a sermon on the Nativity (xxi): "Learn, O Christian, thy worth; and being made a partner of the Divine nature, refuse to return by evil deeds to your former worthlessness." Thirdly, because, "in order to do away with man's presumption, the grace of God is commended in Jesus Christ, though no merits of ours went before," as Augustine says (De Trin. xiii, 17). Fourthly, because "man's pride, which is the greatest stumbling-block to our clinging to God, can be convinced and cured by humility so great," as Augustine says in the same place. Fifthly, in order to free man from the thraldom of sin, which, as Augustine says (De Trin. xiii, 13), "ought to be done in such a way that the devil should be overcome by the justice of the man Jesus Christ," and this was done by Christ satisfying for us. Now a mere man could not have satisfied for the whole human race, and God was not bound to satisfy; hence it behooved Jesus Christ to be both God and man. Hence Pope Leo says in the same sermon: "Weakness is assumed by strength, lowliness by majesty, mortality by eternity, in order that one and the same Mediator of God and men might die in one and rise in the other---for this was our fitting remedy. Unless He was God, He would not have brought a remedy; and unless He was man, He would not have set an example."

And there are very many other advantages which accrued, above man's apprehension.

Reply to Objection 1: This reason has to do with the first kind of necessity, without which we cannot attain to the end.

Reply to Objection 2: Satisfaction may be said to be sufficient in two ways---first, perfectly, inasmuch as it is condign, being adequate to make good the fault committed, and in this way the satisfaction of a mere man cannot be sufficient for sin, both because the whole of human nature has been corrupted by sin, whereas the goodness of any person or persons could not be made up adequately for the harm done to the whole of the nature; and also because a sin committed against God has a kind of infinity from the infinity of the Divine majesty, because the greater the person we offend, the more grievous the offense. Hence for condign satisfaction it was necessary that the act of the one satisfying should have an infinite efficiency, as being of God and man. Secondly, man's satisfaction may be termed sufficient, imperfectly---i.e. in the acceptation of him who is content with it, even though it is not condign, and in this way the satisfaction of a mere man is sufficient. And forasmuch as every imperfect presupposes some perfect thing, by which it is sustained, hence it is that satisfaction of every mere man has its efficiency from the satisfaction of Christ.

Reply to Objection 3: By taking flesh, God did not lessen His majesty; and in consequence did not lessen the reason for reverencing Him, which is increased by the increase of knowledge of Him. But, on the contrary, inasmuch as He wished to draw nigh to us by taking flesh, He greatly drew us to know Him.

Articulus 2

Argumentum 1

Ad secundum sic proceditur. Videtur quod non fuerit necessarium ad reparationem humani generis verbum dei incarnari. Verbo enim dei, cum sit deus perfectus, ut in primo habitum est, nihil virtutis per carnem assumptam accrevit. Si ergo verbum dei incarnatum naturam reparavit, etiam absque carnis assumptione eam potuit reparare.

Argumentum 2

Praeterea, ad reparationem humanae naturae, quae per peccatum collapsa erat, nihil aliud requiri videbatur quam quod homo satisfaceret pro peccato. Non enim deus ab homine requirere plus debet quam possit, et, cum pronior sit ad miserendum quam ad puniendum, sicut homini imputat actum peccati, ita etiam videtur quod ei imputet ad deletionem peccati actum contrarium. Non ergo fuit necessarium ad reparationem humanae naturae verbum dei incarnari.

Argumentum 3

Praeterea, ad salutem hominis praecipue pertinet ut deum revereatur, unde dicitur Malach. I, si ego dominus, ubi timor meus? si pater, ubi honor meus? sed ex hoc ipso homines deum magis reverentur quod eum considerant super omnia elevatum, et ab hominum sensibus remotum, unde in Psalmo dicitur, excelsus super omnes gentes dominus, et super caelos gloria eius; et postea subditur, quis sicut dominus deus noster? quod ad reverentiam pertinet. Ergo videtur non convenire humanae saluti quod deus nobis similis fieret per carnis assumptionem.

Sed Contra

Sed contra, illud per quod humanum genus liberatur a perditione, est necessarium ad humanam salutem. Sed mysterium divinae incarnationis est huiusmodi, secundum illud Ioan. III, sic deus dilexit mundum ut filium suum unigenitum daret, ut omnis qui credit in ipsum non pereat, sed habeat vitam aeternam.

Ergo necesse fuit ad humanam salutem deum incarnari.

Corpus

Respondeo dicendum quod ad finem aliquem dicitur aliquid esse necessarium dupliciter, uno modo, sine quo aliquid esse non potest, sicut cibus est necessarius ad conservationem humanae vitae; alio modo, per quod melius et convenientius pervenitur ad finem, sicut equus necessarius est ad iter. Primo modo deum incarnari non fuit necessarium ad reparationem humanae naturae, deus enim per suam omnipotentem virtutem poterat humanam naturam multis aliis modis reparare. Secundo autem modo necessarium fuit deum incarnari ad humanae naturae reparationem.

Unde dicit Augustinus, XIII de Trin., ostendamus non alium modum possibilem deo defuisse, cuius potestati omnia aequaliter subiacent, sed sanandae miseriae nostrae convenientiorem alium modum non fuisse.

Et hoc quidem considerari potest quantum ad promotionem hominis in bono.

Primo quidem, quantum ad fidem, quae magis certificatur ex hoc quod ipsi deo loquenti credit.

Unde Augustinus dicit, XI de CIV. Dei, ut homo fidentius ambularet ad veritatem, ipsa veritas, dei filius, homine assumpto, constituit atque fundavit fidem.

Secundo, quantum ad spem, quae per hoc maxime erigitur.

Unde Augustinus dicit, XIII de Trin., nihil tam necessarium fuit ad erigendam spem nostram quam ut demonstraretur nobis quantum diligeret nos deus. Quid vero huius rei isto indicio manifestius, quam ut dei filius naturae nostrae dignatus est inire consortium? tertio, quantum ad caritatem, quae maxime per hoc excitatur.

Unde Augustinus dicit, in libro de catechizandis rudibus, quae maior causa est adventus domini, nisi ut ostenderet deus dilectionem suam in nobis? et postea subdit, si amare pigebat, saltem reamare non pigeat.

Quarto, quantum ad rectam operationem, in qua nobis exemplum se praebuit.

Unde Augustinus dicit, in quodam sermone de nativitate domini, homo sequendus non erat, qui videri poterat, deus sequendus erat, qui videri non poterat. Ut ergo exhiberetur homini et qui ab homine videretur, et quem homo sequeretur, deus factus est homo.

Quinto, quantum ad plenam participationem divinitatis, quae vere est hominis beatitudo, et finis humanae vitae.

Et hoc collatum est nobis per christi humanitatem, dicit enim Augustinus, in quodam sermone de nativ. Domini, factus est deus homo, ut homo fieret deus.

Similiter etiam hoc utile fuit ad remotionem mali. Primo enim per hoc homo instruitur ne sibi diabolum praeferat, et eum veneretur, qui est auctor peccati.

Unde dicit Augustinus, XIII de Trin., quando sic deo coniungi potuit humana natura ut fieret una persona, superbi illi maligni spiritus non ideo se audeant homini praeponere quia non habent carnem.

Secundo, quia per hoc instruimur quanta sit dignitas humanae naturae, ne eam inquinemus peccando.

Unde dicit Augustinus, in libro de vera religione, demonstravit nobis deus quam excelsum locum inter creaturas habeat humana natura, in hoc quod hominibus in vero homine apparuit.

Et leo Papa dicit, in sermone de nativitate, agnosce, o christiane, dignitatem tuam, et divinae consors factus naturae, noli in veterem vilitatem degeneri conversatione redire.

Tertio quia, ad praesumptionem hominis tollendam, gratia dei, nullis meritis praecedentibus, in homine christo nobis commendatur, ut dicitur XIII de trinitate.

Quarto, quia superbia hominis, quae maximum impedimentum est ne inhaereatur deo per tantam dei humilitatem redargui potest atque sanari, ut Augustinus dicit ibidem.

Quinto, ad liberandum hominem a servitute.

Quod quidem, ut Augustinus dicit, XIII de Trin., fieri debuit sic ut diabolus iustitia hominis iesu christi superaretur, quod factum est christo satisfaciente pro nobis. Homo autem purus satisfacere non poterat pro toto humano genere; deus autem satisfacere non debebat; unde oportebat deum et hominem esse iesum christum.

Unde et leo Papa dicit, in sermone de nativ., suscipitur a virtute infirmitas, a maiestate humilitas, ut, quod nostris remediis congruebat, unus atque idem dei et hominum mediator et mori ex uno, et resurgere posset ex altero. Nisi enim esset verus deus, non afferret remedium, nisi esset homo verus, non praeberet exemplum.

Sunt autem et aliae plurimae utilitates quae consecutae sunt, supra comprehensionem sensus humani.

Ad 1

Ad primum ergo dicendum quod ratio illa procedit secundum primum modum necessarii, sine quo ad finem perveniri non potest.

Ad 2

Ad secundum dicendum quod aliqua satisfactio potest dici sufficiens dupliciter. Uno modo, perfecte, quia est condigna per quandam adaequationem ad recompensationem commissae culpae. Et sic hominis puri satisfactio sufficiens esse non potuit, quia tota natura humana erat per peccatum corrupta; nec bonum alicuius personae, vel etiam plurium, poterat per aequiparantiam totius naturae detrimentum recompensare. Tum etiam quia peccatum contra deum commissum quandam infinitatem habet ex infinitate divinae maiestatis, tanto enim offensa est gravior, quanto maior est ille in quem delinquitur. Unde oportuit, ad condignam satisfactionem, ut actio satisfacientis haberet efficaciam infinitam, ut puta dei et hominis existens. Alio modo potest dici satisfactio sufficiens imperfecte, scilicet secundum acceptationem eius qui est ea contentus, quamvis non sit condigna. Et hoc modo satisfactio puri hominis est sufficiens. Et quia omne imperfectum praesupponit aliquid perfectum, a quo sustentetur, inde est quod omnis puri hominis satisfactio efficaciam habet a satisfactione christi.

Ad 3

Ad tertium dicendum quod deus, assumendo carnem, suam maiestatem non minuit, et per consequens non minuitur ratio reverentiae ad ipsum. Quae augetur per augmentum cognitionis ipsius. Ex hoc autem quod nobis appropinquare voluit per carnis assumptionem, magis nos ad se cognoscendum attraxit.