Next we must consider the distinction of habitudes, and about this four things are asked. Further, whether many habitudes can be in one power. Second, whether habitudes are distinguished according to objects. Third, whether habitudes are distinguished according to good and bad. Fourth, whether one habitude is constituted from many habitudes.
To the first one proceeds thus. It seems that there are not able to be many habitudes in one power. For with those that are distinguished according to the same thing, one being multiplied, the other is also multiplied. But powers and habitudes are distinguished according to the same thing, namely according to acts and objects. Therefore they are multiplied in similar ways. Therefore there are not able to be many habitudes in one power.
Further, power is a sort of simple impulse [virtus]. But in one simple subject there is not able to be diversity of accidents, because the subject is cause of the accidents, but from one simple thing nothing seems to proceed except one thing. Therefore in one power there is not able to be many habitudes.
Further, just as body is formed through shape, so power is formed through habitude. But one body is not able to be formed all at once by diverse shapes. Therefore neither is one power able to be formed all at once by diverse habitudes. Therefore several habitudes are not able to be all at once in one power.
But contrariwise is that the intellect is a power, in which nonetheless there are habitudes of diverse kinds of knowledge.
I reply that it must be said that, as was said above, habitudes are sorts of dispositions of something existing potentially to something, whether toward nature or to the operation and end of nature. And of those habitudes that are dispositions to nature, it is clearly that there are able to be several in one subject, because the parts of one subject can be taken in diverse ways, according to whose disposition habitudes are named, as, if we take the humors of the parts of the human body, in the way they are disposed according to human nature, there is a habitude or disposition of health, but if we take like parts such as nerves and bones and flesh, in their disposition in ordering to nature, there is strength or weakness, but if we take members such as hands and feet and suchlike, in their disposition of fitness to nature, there is beauty. And thus there are several habitudes or dispositions in the same thing.
But if we speak of habitudes that are dispositions to works, which properly pertain to powers, then there are also can happen to be several habitudes or dispositions in the same thing. The reason for this is that the subject of a habitude is passive power, for active power alone is not subject to any habitude, as is obvious from what is said above. But passive power is compared to the determinate act of one species as matter to form, in that, as matter is determined to one form through one agent, so also passive power by reason of one active object is determined to one act according to species. Thus, just as severalobjects can move one passive power, so one passive power is able to be the subject of diverse acts or completions according to species. But habitudes are sorts of qualities or forms inherent in powers by which power is inclined to determinate acts according to species. Thus to one power several habitudes are able to pertain, just like several acts of different species.
To the first it must therefore be said that, as in natural things diversity of species is according to form, but diversity of genus according to matter, as is said in Metaphys. V, for they are different in genus whose matter is different, so also the diversity of objects according to genus makes for distinction of powers; thus the Philosopher says in Ethic. VI that for things of another genus there are also other compartments of soul. But diversity of objects according to species makes for diversity of acts according to species, and consequently habitudes. Whatever is diverse in genus is also diverse in species, but not vice versa. So too of diverse powers there are diverse species of acts, and diverse habitudes, but it is not needful that diverse habitudes be of diverse powers, but there are able to be several in one. And just as there are genera of genera and species of species, so it can also happen that there are diverse species of habitudes and powers.
To the second it must be said that power, although it is indeed simple according to essence, is nonetheless multiple in impulse [virtute], according as it extends to many acts that differ in species. And thus nothing prohibits there being in one power many habitudes of different species.
To the third it must be said that body is formed through shape as through its proper termination, but habitude is not a termination of power, but is disposition to act as ultimate term. And so there is not able to be several acts all at once in one power, save insofar as one is comprehended under another, just as there cannot be several shapes in one body, save according as one is in the other, like the triangle in the square. For the intellect is not able to understand by many acts all at once. But it can know many things all at once by habitude.
[Thomas Aquinas, Summa Theologiae 2-1.54.1, my translation. The Latin is here, the Dominican Fathers translation is here.
