on as to the
nature of Mind is as out of place here as that about Body. As body is
the unknown exciting cause of sensations, so mind, the other kind of
substance, is the unknown recipient both of the sensations and of all
the other feelings. Though I call a something _myself_, as distinct from
the series of feelings, the 'thread of consciousness,' yet this self
shows itself only through its capacity of feeling or being conscious;
and I can, with my present faculties, conceive the gaining no new
information but about as yet unknown faculties of feeling. In short, as
body is the unsentient cause of all feelings, so mind is the sentient
_subject_ (in the German sense) of them, viz. that which feels them.
About this inner nature we know nothing, and Logic cares nothing.

III. Attributes.--Qualities are the first class of attributes. Now, if
we know nothing about bodies but the sensations they excite, we can mean
nothing by the attributes of bodies but sensations. Against this it has
been urged that, though we know nothing of sensible objects except the
sensations, the quality which we ascribe on the _ground_ of the
sensation may yet be a real hidden power or quality in the object, of
which the sensation is only the evidence. Seemingly, this doctrine
arises only from the tendency to suppose that there must be two
different things to answer to two names when not quite synonymous.
Quality and sensation are probably names for the same thing viewed in
different lights. The doctrine of an entity _per se_, called quality, is
a relic of the scholastic _occult causes_; the only intelligible cause
of sensation being the presence of the assemblage of phenomena, called
the _object_. Why the presence of the object causes the sensation, we
know not; and, granting an _occult cause_, we are still in the dark as
to how _that_ produces the effect. However, the question belongs to
metaphysics; and it suits this doctrine, as well as the opposed one, to
say that a quality has for its _foundation_ a sensation.

Relations form the second class of attributes. In all cases of relation
there exists some fact into which the relatives enter as parties
concerned; and this is the _fundamentum relationis_. Whenever two things
are involved in some one fact, we may ascribe to them a relation
grounded on it, however general the fact may be. As, then, a quality is
an attribute based on the fact of a sensation, so a relation is an
attribute based on a fact i