Treatise on Habits (part 1-2a)

Reply Obj. 3: Bodily dispositions which are in the first species of quality, as some maintained, differ from qualities of the third species, in this, that the qualities of the third species consist in some "becoming" and movement, as it were, wherefore they are called passions or passible qualities. But when they have attained to perfection (specific perfection, so to speak), they have then passed into the first species of quality. But Simplicius in his Commentary disapproves of this; for in this way heating would be in the third species, and heat in the first species of quality; whereas Aristotle puts heat in the third. Wherefore Porphyrius, as Simplicius reports (Commentary), says that passion or passion-like quality, disposition and habit, differ in bodies by way of intensity and remissness. For when a thing receives heat in this only that it is being heated, and not so as to be able to give heat, then we have passion, if it is transitory; or passion-like quality if it is permanent. But when it has been brought to the point that it is able to heat something else, then it is a disposition; and if it goes so far as to be firmly fixed and to become difficult to change, then it will be a habit: so that disposition would be a certain intensity of passion or passion-like quality, and habit an intensity or disposition. But Simplicius disapproves of this, for such intensity and remissness do not imply diversity on the part of the form itself, but on the part of the diverse participation thereof by the subject; so that there would be no diversity among the species of quality. And therefore we must say otherwise that, as was explained above (Q. 49, A. 2, ad 1), the adjustment of the passion-like qualities themselves, according to their suitability to nature, implies the notion of disposition: and so, when a change takes place in these same passion-like qualities, which are heat and cold, moisture and dryness, there results a change as to sickness and health.…