Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that in the angel to understand is to exist. For in living things to live is to be, as the Philosopher says (De Anima ii, text. 37). But to "understand is in a sense to live" (De Anima ii, text. 37). Therefore in the angel to understand is to exist.

Objection 2: Further, cause bears the same relation to cause, as effect to effect. But the form whereby the angel exists is the same as the form by which he understands at least himself. Therefore in the angel to understand is to exist.

On the contrary, The angel's act of understanding is his movement, as is clear from Dionysius (Div. Nom. iv). But to exist is not movement. Therefore in the angel to be is not to understand.

I answer that, The action of the angel, as also the action of any creature, is not his existence. For as it is said (Metaph. ix, text. 16), there is a twofold class of action; one which passes out to something beyond, and causes passion in it, as burning and cutting; and another which does not pass outwards, but which remains within the agent, as to feel, to understand, to will; by such actions nothing outside is changed, but the whole action takes place within the agent. It is quite clear regarding the first kind of action that it cannot be the agent's very existence: because the agent's existence is signified as within him, while such an action denotes something as issuing from the agent into the thing done. But the second action of its own nature has infinity, either simple or relative. As an example of simple infinity, we have the act "to understand," of which the object is "the true"; and the act "to will," of which the object is "the good"; each of which is convertible with being; and so, to understand and to will, of themselves, bear relation to all things, and each receives its species from its object. But the act of sensation is relatively infinite, for it bears relation to all sensible things; as sight does to all things visible. Now the being of every creature is restricted to one in genus and species; God's being alone is simply infinite, comprehending all things in itself, as Dionysius says (Div. Nom. v). Hence the Divine nature alone is its own act of understanding and its own act of will.

Reply to Objection 1: Life is sometimes taken for the existence of the living subject: sometimes also for a vital operation, that is, for one whereby something is shown to be living. In this way the Philosopher says that to understand is, in a sense, to live: for there he distinguishes the various grades of living things according to the various functions of life.

Reply to Objection 2: The essence of an angel is the reason of his entire existence, but not the reason of his whole act of understanding, since he cannot understand everything by his essence. Consequently in its own specific nature as such an essence, it is compared to the existence of the angel, whereas to his act of understanding it is compared as included in the idea of a more universal object, namely, truth and being. Thus it is evident, that, although the form is the same, yet it is not the principle of existence and of understanding according to the same formality. On this account it does not follow that in the angel "to be" is the same as 'to understand.'

Articulus 2

Argumentum 1

Ad secundum sic proceditur. Videtur quod intelligere Angeli sit eius esse.

Vivere enim viventibus est esse, ut dicitur in II de anima.

Sed intelligere est quoddam vivere, ut in eodem dicitur.

Ergo intelligere Angeli est eius esse.

Argumentum 2

Praeterea, sicut se habet causa ad causam, ita effectus ad effectum. Sed forma per quam Angelus est, est eadem cum forma per quam intelligit ad minus seipsum.

Ergo eius intelligere est idem cum suo esse.

Sed Contra

Sed contra, intelligere Angeli est motus eius; ut patet per dionysium, IV cap. De div. Nom..

Sed esse non est motus. Ergo esse Angeli non est intelligere eius.

Corpus

Respondeo dicendum quod actio Angeli non est eius esse, neque actio alicuius creaturae. Duplex enim est actionis genus, ut dicitur IX metaphys..

Una scilicet actio est quae transit in aliquid exterius, inferens ei passionem, sicut urere et secare.

Alia vero actio est quae non transit in rem exteriorem, sed manet in ipso agente, sicut sentire, intelligere et velle, per huiusmodi enim actionem non immutatur aliquid extrinsecum, sed totum in ipso agente agitur. De prima ergo actione manifestum est quod non potest esse ipsum esse agentis, nam esse agentis significatur intra ipsum, actio autem talis est effluxus in actum ab agente.

Secunda autem actio de sui ratione habet infinitatem, vel simpliciter, vel secundum quid. Simpliciter quidem, sicut intelligere, cuius obiectum est verum, et velle, cuius obiectum est bonum, quorum utrumque convertitur cum ente; et ita intelligere et velle, quantum est de se, habent se ad omnia; et utrumque recipit speciem ab obiecto. Secundum quid autem infinitum est sentire, quod se habet ad omnia sensibilia, sicut visus ad omnia visibilia. Esse autem cuiuslibet creaturae est determinatum ad unum secundum genus et speciem, esse autem solius dei est simpliciter infinitum, in se omnia comprehendens, ut dicit dionysius, V cap. De div. Nom..

Unde solum esse divinum est suum intelligere et suum velle.

Ad 1

Ad primum ergo dicendum quod vivere quandoque sumitur pro ipso esse viventis, quandoque vero pro operatione vitae, idest per quam demonstratur aliquid esse vivens.

Et hoc modo philosophus dicit quod intelligere est vivere quoddam, ibi enim distinguit diversos gradus viventium secundum diversa opera vitae.

Ad 2

Ad secundum dicendum quod ipsa essentia Angeli est ratio totius sui esse, non autem est ratio totius sui intelligere, quia non omnia intelligere potest per suam essentiam. Et ideo secundum propriam rationem, inquantum est talis essentia, comparatur ad ipsum esse Angeli. Sed ad eius intelligere comparatur secundum rationem universalioris obiecti, scilicet veri vel entis.

Et sic patet quod, licet sit eadem forma, non tamen secundum eandem rationem est principium essendi et intelligendi. Et propter hoc non sequitur quod in Angelo sit idem esse et intelligere.