Certain experiences are accepted as signs, and certain others come to take the more dignified position of thing signified; the mind rests in them and regards them as the real.
We have seen above that the world of real things in which the plain man finds himself is a world of objects revealed in experiences of touch.
When he asks regarding anything: How far away is it?
How big is it?
In what direction is it?
it is always the touch thing that interests him.

What is given to the other senses is only a sign of this.
We have also seen (section 8) that the world of atoms and molecules of which the man of science tells us is nothing more than a further development of the world of the plain man.

The real things with which science concerns itself are, after all, only minute touch things, conceived just as are the things with which the plain man is familiar.
They exist in space and move about in space, as the things about us are perceived to exist in space and move about in space.

They have size and position, and are separated by distances.

We do not _perceive_ them, it is true; but we _conceive_ them after the analogy of the things that we do perceive, and it is not inconceivable that, if our senses were vastly more acute, we might perceive them directly.
Now, when we conclude that the things directly perceptible to the sense of touch are to be regarded as appearances, as signs of the presence of these minuter things, do we draw such a conclusion arbitrarily?
By no means.