The vegetative power present in the whole body communicates to every
part thereof a trace of the soul. It is therefore to the entire body
that we must refer suffering, pleasure, and the desire of food. Though
nothing definite is ascertained about the seat of sexual desire, let us
grant that their seat is in the organs destined to its satisfaction.
Further, be it granted that the liver is the seat of the soul's faculty
of desire, because that organ is particularly the theatre of the
activities of the vegetative power which impresses a trace of the soul
on the body; and further, because it is from the liver that the action
it exercises starts.