Amor pertinet ad concupiscibilem, quia dicitur per respectum ad bonum absolute, non per respectum ad arduum, quod est obiectum irascibilis.
Love belongs to the concupiscible power, because it regards good absolutely, and not under the aspect of difficulty, which is the object of the irascible faculty.
Amor dicitur illud quod est principium motus tendentis in finem amatum. In appetitu autem naturali, principium huiusmodi motus est connaturalitas appetentis ad id in quod tendit, quae dici potest amor naturalis.
The name "love" is given to the principle of movement towards the end loved. In the natural appetite, the principle of this movement is the appetitive subject's connaturalness with the thing to which it tends, and may be called "natural love".
Et similiter coaptatio appetitus sensitivi, vel voluntatis, ad aliquod bonum, idest ipsa complacentia boni, dicitur amor sensitivus, vel intellectivus seu rationalis. Amor igitur sensitivus est in appetitu sensitivo, sicut amor intellectivus in appetitu intellectivo.
In like manner the aptitude of the sensitive appetite, or of the will, to some good, that is to say, its very complacency in good is called "sensitive love," or "intellectual" or "rational love." So that sensitive love is in the sensitive appetite, just as intellectual love is in the intellectual appetite.
Philosophus dicit, in II Topic., quod "amor est in concupiscibili".
The Philosopher says (Topic. ii, 7) that "love is in the concupiscible power".