Three Types of Activity
Exhalation and inhalation are bodily activity, reasoning and investigation are vocal activity, perception and feeling are mental activity.
This text is part of the same discussion as No. 10.
It is remarkable that thought processes are called an activity of speech. Dr Watson, the well-known behaviorist psychologist, tried to introduce the same idea. Perhaps it was believed that thought processes were always presented psychologically in the form of verbal ideas. From text No. 38, which uses the same words for thought processes, it is anyhow clear that spoken words are not intended.