Tahafut_al-Tahafut-transl-Engl-van-den-Bergh

power to move when, in the representative faculty which we
have mentioned, ‘ there is inscribed the form of something to
be sought or avoided. The stimulating faculty has two
branches, one called concupiscent which excites to a
movement, through which there is an approach to the things
represented as necessary or useful in a search for pleasure,
and the irascible which excites to a movement through which
the thing represented as injurious or mischievous is removed
as one seeks to master it. Through this faculty the complete
determination to act is effected, which is called will.
The motive faculty which itself executes movement is a
faculty which is diffused in the nerves and muscles and has
the function of contracting the muscles and drawing the
tendons and ligaments which are in contact with the limbs in
the direction where this faculty resides, or of relaxing and
extending them so that the ligaments and tendons move in
the opposite direction . These are the animal faculties of the
soul as described in a summary way, without the details.
And as regards the soul which thinks things and is called
the rational or discursive soul by the philosophers (and by
‘discursive’ is meant ‘rational’, because discourse is the most
typical external operation of reason and therefore the
intellective soul takes its name from it), it has two faculties, a
knowing and an acting, and both are called intellect, though
equivocally. b And the acting faculty is one which is a
principle moving man’s body towards the well-ordered
human arts, whose order derives from the deliberation
proper to man. The knowing faculty, which is called the
speculative, is one which has the function of perceiving the
real natures of the intelligibles in abstraction from matter,
place, and position; and these are the universal concepts
which the theologians call sometimes conditions and
sometimes modes, ‘ and which the philosophers call abstract
universals.
The soul has therefore two faculties on two sides: the
speculative faculty on the side of the angels, since through it
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