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

and differs from it and determines a plurality, and on this
assumption it is not possible that knowledge should attach
itself to two objects of knowledge without this implying a
greater and more important kind of plurality than that which
is intended in the assumption of an existence, brought in
relation to a quiddity. And as to the knowledge of a son and
similarly of other relative concepts, there is in it a plurality,
since there must necessarily be knowledge of the son
himself and the father himself, and this is a dual knowledge,
and there must be a third knowledge, and this is the relation;
indeed, this third knowledge is implied in the dual knowledge
which precedes it, as they are its necessary condition, for as
long as the terms of relation are not known previously, the
relation itself cannot be known, and there is thus a plurality
of knowledge of which one part is conditioned through
another. Likewise when the First knows itself as related to
the other genera and species by being their principle, it
needs the knowledge of its own essence and of the single
genera and it must further know that there exists between
itself and those genera and species the relation of being a
principle, for otherwise the existence of this relation could
not be supposed to be known to it. And as to their statement
that he who knows something knows that he is knowing
through this knowledge itself, so that the thing known can be
manifold, but the knowledge remains one, this is not true; on
the contrary, he knows that he knows through another
knowledge, and this ends in a knowledge to which he does
not pay attention and of which he is no longer conscious,
and we do not say that there is an infinite regress, but there
is a final term of knowledge attached to the thing known, and
he is unconscious of the existence of the knowledge, but not
of the existence of the known, like a man who knows the
colour black and whose soul at the moment of his knowing it
is plunged in the object of his knowledge, the colour black,
and who is unconscious of his knowing this colour black and
whose attention is not centred on it, for if it were, he would
need another knowledge till his attention came to a stand. ‘
282