The fact that we act is of course as important as the fact that we think or the fact that we feel; and the distinction which separates thought and action should not be made too sharp.
Yet there is a distinction.

To understand action we must again go to introspection.

This comes out as soon as we ask how we reach our knowledge of the actions of others.

Of course, we say at once that we see them.

And that is true; we do see them, while as to their thoughts we only infer them from what we see of their action.