re acts and the
reason why He exists are one and the same. Since, therefore, He exists
for no end, He acts for no end; and since He has no principle or end of
existence, He has no principle or end of action. A final cause, as it is
called, is nothing, therefore, but human desire, in so far as this is
considered as the principle or primary cause of anything. For example,
when we say that the having a house to live in was the final cause of
this or that house, we merely mean that a man, because he imagined the
advantages of a domestic life, desired to build a house. Therefore,
having a house to live in, in so far as it is considered as a final
cause, is merely this particular desire, which is really an efficient
cause, and is considered as primary, because men are usually ignorant of
the causes of their desires; for, as I have often said, we are conscious
of our actions and desires, but ignorant of the causes by which we are
determined to desire anything. As for the vulgar opinion that Nature
sometimes fails or commits an error, or produces imperfect things, I
class it amongst those fictions mentioned above.[29]

Perfection, therefore, and imperfection are really only modes of
thought; that is to say, notions which we are in the habit of forming
from the comparison with one another of individuals of the same species
or genus, and this is the reason why I have said that by reality and
perfection I understand the same thing; for we are in the habit of
referring all individuals in Nature to one genus, which is called the
most general; that is to say, to the notion of being, which embraces
absolutely all the individual objects in Nature. In so far, therefore,
as we refer the individual objects in Nature to this genus, and compare
them one with another, and discover that some possess more being or
reality than others, in so far do we call some more perfect than others;
and in so far as we assign to the latter anything which, like
limitation, termination, impotence, etc., involves negation, shall we
call them imperfect, because they do not affect our minds so strongly as
those we call perfect, but not because anything which really belongs to
them is wanting, or because Nature has committed an error. For nothing
belongs to the nature of anything excepting that which follows from the
necessity of the nature of the efficient cause, and whatever follows
from the necessity of the nature of the efficient cause necessarily
happens.