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

I say:
acutely, because this expression is employed
metaphorically; for since nature is in a certain way a cause
and the agent is also a cause, nature is called an agent
metaphorically. The expression ‘voluntary act’ is as much
redundant as the expression ‘he wills and knows what he
wills’.
This statement is undoubtedly wrong, for what actualizes another thing,
i.e. acts on it, is not called agent simply by a metaphor, but in reality, for
the definition of ‘agent’ is appropriate to it. The division of ‘agent’ into
‘natural’ and ‘voluntary agent’ is not the division of an equivocal term, but
the division of a genus. Therefore the division of ‘agent’ into ‘natural’ and
‘voluntary agent’ is right, since that which actualizes another can also be
divided into these two classes.
Ghazali says:
I say:
However, as it can happen that ‘act’ is used
metaphorically and also in its real sense, people have no
objection in saying ‘someone acted voluntarily’, meaning that
he acted not in a metaphorical sense, but really, in the way
in which it is said ‘he spoke with his tongue’, or ‘he saw with
his eye’. For, since one is permitted to rise ‘heart’
metaphorically for ‘sight’, and motion of the head or hand for
word-for one can say ‘He nodded assent’-it is not wrong to
say ‘He spoke with his tongue and he saw with his eye’, in
order to exclude any idea of metaphor. This is a delicate
point, but let us be careful to heed the place where those
stupid people slipped.
Certainly it is a delicate point that a man with scientific pretensions should
give such a bad example and such a false reason to explain the
repugnance people seem to have in admitting the division of ‘act’ into
‘natural’ and ‘voluntary act’. No one ever says ‘He saw with his eye, and
he saw without his eye’ in the belief that this is a division of sight; we only
say ‘He saw with his eye’ to emphasize the fact that real sight is meant,
144