things signified, or to think them of the same species, as we
are visible and tangible ideas. But a little consideration will show us
how this may be without our supposing them of a like nature. These signs
are constant and universal, their connexion with tangible ideas has been
learnt at our first entrance into the world; and ever since, almost every
moment of our lives, it has been occurring to our thoughts, and fastening
and striking deeper on our minds. When we observe that signs are
variable, and of human institution; when we remember there was a time
they were not connected in our minds with those things they now so
readily suggest; but that their signification was learned by the slow
steps of experience: this preserves us from confounding them. But when we
find the same signs suggest the same things all over the world; when we
know they are not of human institution, and cannot remember that we ever
learned their signification, but think that at first sight they would
have suggested to us the same things they do now: all this persuades us
they are of the same species as the things respectively represented by
them, and that it is by a natural resemblance they suggest them to our
minds.

145. Add to this that whenever we make a nice survey of any object,
successively directing the optic axis to each point thereof, there are
certain lines and figures described by the motion of the head or eye,
which being in truth perceived by feeling, do nevertheless so mix
themselves, as it were, with the ideas of sight, that we can scarce think
but they appertain to that sense. Again, the ideas of sight enter into
the mind several at once, more distinct and unmingled than is usual in
the other senses beside the touch. Sounds, for example, perceived at the
same instant, are apt to coalesce, if I may so say, into one sound: but
we can perceive at the same time great variety of visible objects, very
separate and distinct from each other. Now tangible extension being made
up of several distinct coexistent parts, we may hence gather another
reason that may dispose us to imagine a likeness or an analogy between
the immediate objects of sight and touch. But nothing, certainly, doth
more contribute to blend and confound them together than the strict and
close connexion they have with each other. We cannot open our eyes but
the ideas of distance, bodies, and tangible figures are suggested by
them. So swift and sudden and unperceived is the