Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that the intelligible species abstracted from the phantasm is related to our intellect as that which is understood. For the understood in act is in the one who understands: since the understood in act is the intellect itself in act. But nothing of what is understood is in the intellect actually understanding, save the abstracted intelligible species. Therefore this species is what is actually understood.

Objection 2: Further, what is actually understood must be in something; else it would be nothing. But it is not in something outside the soul: for, since what is outside the soul is material, nothing therein can be actually understood. Therefore what is actually understood is in the intellect. Consequently it can be nothing else than the aforesaid intelligible species.

Objection 3: Further, the Philosopher says (1 Peri Herm. i) that "words are signs of the passions in the soul." But words signify the things understood, for we express by word what we understand. Therefore these passions of the soul---viz. the intelligible species, are what is actually understood.

On the contrary, The intelligible species is to the intellect what the sensible image is to the sense. But the sensible image is not what is perceived, but rather that by which sense perceives. Therefore the intelligible species is not what is actually understood, but that by which the intellect understands.

I answer that, Some have asserted that our intellectual faculties know only the impression made on them; as, for example, that sense is cognizant only of the impression made on its own organ. According to this theory, the intellect understands only its own impression, namely, the intelligible species which it has received, so that this species is what is understood.

This is, however, manifestly false for two reasons. First, because the things we understand are the objects of science; therefore if what we understand is merely the intelligible species in the soul, it would follow that every science would not be concerned with objects outside the soul, but only with the intelligible species within the soul; thus, according to the teaching of the Platonists all science is about ideas, which they held to be actually understood . Secondly, it is untrue, because it would lead to the opinion of the ancients who maintained that "whatever seems, is true" , and that consequently contradictories are true simultaneously. For if the faculty knows its own impression only, it can judge of that only. Now a thing seems according to the impression made on the cognitive faculty. Consequently the cognitive faculty will always judge of its own impression as such; and so every judgment will be true: for instance, if taste perceived only its own impression, when anyone with a healthy taste perceives that honey is sweet, he would judge truly; and if anyone with a corrupt taste perceives that honey is bitter, this would be equally true; for each would judge according to the impression on his taste. Thus every opinion would be equally true; in fact, every sort of apprehension.

Therefore it must be said that the intelligible species is related to the intellect as that by which it understands: which is proved thus. There is a twofold action (Metaph. ix, Did. viii, 8), one which remains in the agent; for instance, to see and to understand; and another which passes into an external object; for instance, to heat and to cut; and each of these actions proceeds in virtue of some form. And as the form from which proceeds an act tending to something external is the likeness of the object of the action, as heat in the heater is a likeness of the thing heated; so the form from which proceeds an action remaining in the agent is the likeness of the object. Hence that by which the sight sees is the likeness of the visible thing; and the likeness of the thing understood, that is, the intelligible species, is the form by which the intellect understands. But since the intellect reflects upon itself, by such reflection it understands both its own act of intelligence, and the species by which it understands. Thus the intelligible species is that which is understood secondarily; but that which is primarily understood is the object, of which the species is the likeness. This also appears from the opinion of the ancient philosophers, who said that "like is known by like." For they said that the soul knows the earth outside itself, by the earth within itself; and so of the rest. If, therefore, we take the species of the earth instead of the earth, according to Aristotle (De Anima iii, 8), who says "that a stone is not in the soul, but only the likeness of the stone"; it follows that the soul knows external things by means of its intelligible species.

Reply to Objection 1: The thing understood is in the intellect by its own likeness; and it is in this sense that we say that the thing actually understood is the intellect in act, because the likeness of the thing understood is the form of the intellect, as the likeness of a sensible thing is the form of the sense in act. Hence it does not follow that the intelligible species abstracted is what is actually understood; but rather that it is the likeness thereof.

Reply to Objection 2: In these words "the thing actually understood" there is a double implication---the thing which is understood, and the fact that it is understood. In like manner the words "abstract universal" imply two things, the nature of a thing and its abstraction or universality. Therefore the nature itself to which it occurs to be understood, abstracted or considered as universal is only in individuals; but that it is understood, abstracted or considered as universal is in the intellect. We see something similar to this is in the senses. For the sight sees the color of the apple apart from its smell. If therefore it be asked where is the color which is seen apart from the smell, it is quite clear that the color which is seen is only in the apple: but that it be perceived apart from the smell, this is owing to the sight, forasmuch as the faculty of sight receives the likeness of color and not of smell. In like manner humanity understood is only in this or that man; but that humanity be apprehended without conditions of individuality, that is, that it be abstracted and consequently considered as universal, occurs to humanity inasmuch as it is brought under the consideration of the intellect, in which there is a likeness of the specific nature, but not of the principles of individuality.

Reply to Objection 3: There are two operations in the sensitive part. One, in regard of impression only, and thus the operation of the senses takes place by the senses being impressed by the sensible. The other is formation, inasmuch as the imagination forms for itself an image of an absent thing, or even of something never seen. Both of these operations are found in the intellect. For in the first place there is the passion of the passive intellect as informed by the intelligible species; and then the passive intellect thus informed forms a definition, or a division, or a composition, expressed by a word. Wherefore the concept conveyed by a word is its definition; and a proposition conveys the intellect's division or composition. Words do not therefore signify the intelligible species themselves; but that which the intellect forms for itself for the purpose of judging of external things.

Articulus 2

Argumentum 1

Ad secundum sic proceditur. Videtur quod species intelligibiles a phantasmatibus abstractae, se habeant ad intellectum nostrum sicut id quod intelligitur. Intellectum enim in actu est in intelligente, quia intellectum in actu est ipse intellectus in actu. Sed nihil de re intellecta est in intellectu actu intelligente, nisi species intelligibilis abstracta.

Ergo huiusmodi species est ipsum intellectum in actu.

Argumentum 2

Praeterea, intellectum in actu oportet in aliquo esse, alioquin nihil esset. Sed non est in re quae est extra animam, quia, cum res extra animam sit materialis, nihil quod est in ea, potest esse intellectum in actu. Relinquitur ergo quod intellectum in actu sit in intellectu. Et ita nihil est aliud quam species intelligibilis praedicta.

Argumentum 3

Praeterea, philosophus dicit, in I periherm., quod voces sunt notae earum quae sunt in anima passionum.

Sed voces significant res intellectas, id enim voce significamus quod intelligimus. Ergo ipsae passiones animae, scilicet species intelligibiles, sunt ea quae intelliguntur in actu.

Sed Contra

Sed contra, species intelligibilis se habet ad intellectum, sicut species sensibilis ad sensum. Sed species sensibilis non est illud quod sentitur, sed magis id quo sensus sentit. Ergo species intelligibilis non est quod intelligitur actu, sed id quo intelligit intellectus.

Corpus

Respondeo dicendum quod quidam posuerunt quod vires cognoscitivae quae sunt in nobis, nihil cognoscunt nisi proprias passiones; puta quod sensus non sentit nisi passionem sui organi. Et secundum hoc, intellectus nihil intelligit nisi suam passionem, idest speciem intelligibilem in se receptam. Et secundum hoc, species huiusmodi est ipsum quod intelligitur.

Sed haec opinio manifeste apparet falsa ex duobus. Primo quidem, quia eadem sunt quae intelligimus, et de quibus sunt scientiae.

Si igitur ea quae intelligimus essent solum species quae sunt in anima, sequeretur quod scientiae omnes non essent de rebus quae sunt extra animam, sed solum de speciebus intelligibilibus quae sunt in anima; sicut secundum Platonicos omnes scientiae sunt de ideis, quas ponebant esse intellecta in actu.

Secundo, quia sequeretur error antiquorum dicentium quod omne quod videtur est verum; et sic quod contradictoriae essent simul verae. Si enim potentia non cognoscit nisi propriam passionem, de ea solum iudicat. Sic autem videtur aliquid, secundum quod potentia cognoscitiva afficitur. Semper ergo iudicium potentiae cognoscitivae erit de eo quod iudicat, scilicet de propria passione, secundum quod est; et ita omne iudicium erit verum.

Puta si gustus non sentit nisi propriam passionem, cum aliquis habens sanum gustum iudicat mel esse dulce, vere iudicabit; et similiter si ille qui habet gustum infectum, iudicet mel esse amarum, vere iudicabit, uterque enim iudicat secundum quod gustus eius afficitur. Et sic sequitur quod omnis opinio aequaliter erit vera, et universaliter omnis acceptio.

Et ideo dicendum est quod species intelligibilis se habet ad intellectum ut quo intelligit intellectus. Quod sic patet.

Cum enim sit duplex actio, sicut dicitur IX metaphys., una quae manet in agente, ut videre et intelligere, altera quae transit in rem exteriorem, ut calefacere et secare; utraque fit secundum aliquam formam. Et sicut forma secundum quam provenit actio tendens in rem exteriorem, est similitudo obiecti actionis, ut calor calefacientis est similitudo calefacti; similiter forma secundum quam provenit actio manens in agente, est similitudo obiecti. Unde similitudo rei visibilis est secundum quam visus videt; et similitudo rei intellectae, quae est species intelligibilis, est forma secundum quam intellectus intelligit.

Sed quia intellectus supra seipsum reflectitur, secundum eandem reflexionem intelligit et suum intelligere, et speciem qua intelligit. Et sic species intellectiva secundario est id quod intelligitur. Sed id quod intelligitur primo, est res cuius species intelligibilis est similitudo.

Et hoc etiam patet ex antiquorum opinione, qui ponebant simile simili cognosci. Ponebant enim quod anima per terram quae in ipsa erat, cognosceret terram quae extra ipsam erat; et sic de aliis.

Si ergo accipiamus speciem terrae loco terrae, secundum doctrinam Aristotelis, qui dicit quod lapis non est in anima, sed species lapidis; sequetur quod anima per species intelligibiles cognoscat res quae sunt extra animam.

Ad 1

Ad primum ergo dicendum quod intellectum est in intelligente per suam similitudinem. Et per hunc modum dicitur quod intellectum in actu est intellectus in actu, inquantum similitudo rei intellectae est forma intellectus; sicut similitudo rei sensibilis est forma sensus in actu. Unde non sequitur quod species intelligibilis abstracta sit id quod actu intelligitur, sed quod sit similitudo eius.

Ad 2

Ad secundum dicendum quod, cum dicitur intellectum in actu, duo importantur, scilicet res quae intelligitur, et hoc quod est ipsum intelligi. Et similiter cum dicitur universale abstractum, duo intelliguntur, scilicet ipsa natura rei, et abstractio seu universalitas. Ipsa igitur natura cui accidit vel intelligi vel abstrahi, vel intentio universalitatis, non est nisi in singularibus; sed hoc ipsum quod est intelligi vel abstrahi, vel intentio universalitatis, est in intellectu. Et hoc possumus videre per simile in sensu. Visus enim videt colorem pomi sine eius odore. Si ergo quaeratur ubi sit color qui videtur sine odore manifestum est quod color qui videtur, non est nisi in pomo; sed quod sit sine odore perceptus, hoc accidit ei ex parte visus, inquantum in visu est similitudo coloris et non odoris.

Similiter humanitas quae intelligitur, non est nisi in hoc vel in illo homine, sed quod humanitas apprehendatur sine individualibus conditionibus, quod est ipsam abstrahi, ad quod sequitur intentio universalitatis, accidit humanitatis secundum quod percipitur ab intellectu, in quo est similitudo naturae speciei, et non individualium principiorum.

Ad 3

Ad tertium dicendum quod in parte sensitiva invenitur duplex operatio. Una secundum solam immutationem, et sic perficitur operatio sensus per hoc quod immutatur a sensibili.

Alia operatio est formatio, secundum quod vis imaginativa format sibi aliquod idolum rei absentis, vel etiam nunquam visae.

Et utraque haec operatio coniungitur in intellectu. Nam primo quidem consideratur passio intellectus possibilis secundum quod informatur specie intelligibili. Qua quidem formatus, format secundo vel definitionem vel divisionem vel compositionem, quae per vocem significatur. Unde ratio quam significat nomen, est definitio; et enuntiatio significat compositionem et divisionem intellectus. Non ergo voces significant ipsas species intelligibiles; sed ea quae intellectus sibi format ad iudicandum de rebus exterioribus.