Friday, February 20, 2009

Q78 A3: Whether the five exterior senses are properly distinguished?

Yes. The Philosopher says (De Anima iii, 1): "There is no other besides the five senses." The reason of the number and distinction of the exterior senses must be ascribed to that which belongs to the senses properly and "per se."

Philosophus dicit, in III de anima, quod "non est alter sensus praeter quinque". Accipienda est ratio numeri et distinctionis exteriorum sensuum, secundum illud quod proprie et per se ad sensum pertinet.

Now, sense is a passive power, and is naturally immuted by the exterior sensible. Wherefore the exterior cause of such immutation is what is "per se" perceived by the sense, and according to the diversity of that exterior cause are the sensitive powers diversified.

Est autem sensus quaedam potentia passiva, quae nata est immutari ab exteriori sensibili. Exterius ergo immutativum est quod per se a sensu percipitur, et secundum cuius diversitatem sensitivae potentiae distinguuntur.

Now, immutation is of two kinds, one natural, the other spiritual. Natural immutation takes place by the form of the immuter being received according to its natural existence, into the thing immuted, as heat is received into the thing heated. Whereas spiritual immutation takes place by the form of the immuter being received, according to a spiritual mode of existence, into the thing immuted, as the form of color is received into the pupil which does not thereby become colored. Now, for the operation of the senses, a spiritual immutation is required, whereby an intention of the sensible form is effected in the sensile organ. Otherwise, if a natural immutation alone sufficed for the sense's action, all natural bodies would feel when they undergo alteration.

Est autem duplex immutatio, una naturalis, et alia spiritualis. Naturalis quidem, secundum quod forma immutantis recipitur in immutato secundum esse naturale, sicut calor in calefacto. Spiritualis autem, secundum quod forma immutantis recipitur in immutato secundum esse spirituale; ut forma coloris in pupilla, quae non fit per hoc colorata. Ad operationem autem sensus requiritur immutatio spiritualis, per quam intentio formae sensibilis fiat in organo sensus. Alioquin, si sola immutatio naturalis sufficeret ad sentiendum, omnia corpora naturalia sentirent dum alterantur.

For the powers are not for the organs, but the organs for the powers; wherefore there are not various powers for the reason that there are various organs; on the contrary, for this has nature provided a variety of organs, that they might be adapted to various powers. In the same way nature provided various mediums for the various senses, according to the convenience of the acts of the powers. And to be cognizant of the natures of sensible qualities does not pertain to the senses, but to the intellect.

Non enim potentiae sunt propter organa, sed organa propter potentias, unde non propter hoc sunt diversae potentiae, quia sunt diversa organa; sed ideo natura instituit diversitatem in organis, ut congruerent diversitati potentiarum. Et similiter diversa media diversis sensibus attribuit, secundum quod erat conveniens ad actus potentiarum. Naturas autem sensibilium qualitatum cognoscere non est sensus, sed intellectus.

Size, shape, and the like, which are called "common sensibles," are midway between "accidental sensibles" and "proper sensibles," which are the objects of the senses. For the proper sensibles first, and of their very nature, affect the senses; since they are qualities that cause alteration. But the common sensibles are all reducible to quantity. As to size and number, it is clear that they are species of quantity. Shape is a quality about quantity. Shape is a quality about quantity, since the notion of shape consists of fixing the bounds of magnitude. Movement and rest are sensed according as the subject is affected in one or more ways in the magnitude of the subject or of its local distance, as in the movement of growth or of locomotion, or again, according as it is affected in some sensible qualities, as in the movement of alteration; and thus to sense movement and rest is, in a way, to sense one thing and many. Now quantity is the proximate subject of the qualities that cause alteration, as surface is of color. Therefore the common sensibles do not move the senses first and of their own nature, but by reason of the sensible quality; as the surface by reason of color. Yet they are not accidental sensibles, for they produce a certain variety in the immutation of the senses.

Magnitudo et figura et huiusmodi, quae dicuntur communia sensibilia, sunt media inter sensibilia per accidens et sensibilia propria, quae sunt obiecta sensuum. Nam sensibilia propria primo et per se immutant sensum; cum sint qualitates alterantes. Sensibilia vero communia omnia reducuntur ad quantitatem. Et de magnitudine quidem et numero, patet quod sunt species quantitatis. Figura autem est qualitas circa quantitatem; cum consistat ratio figurae in terminatione magnitudinis. Motus autem et quies sentiuntur, secundum quod subiectum uno modo vel pluribus modis se habet secundum magnitudinem subiecti vel localis distantiae, quantum ad motum augmenti et motum localem; vel etiam secundum sensibiles qualitates, ut in motu alterationis, et sic sentire motum et quietem est quodammodo sentire unum et multa. Quantitas autem est proximum subiectum qualitatis alterativae, ut superficies coloris. Et ideo sensibilia communia non movent sensum primo et per se, sed ratione sensibilis qualitatis; ut superficies ratione coloris. Nec tamen sunt sensibilia per accidens, quia huiusmodi sensibilia aliquam diversitatem faciunt in immutatione sensus.