By this we exhort others; by this we persuade them; by this we comfort the afflicted; by this we deliver the affrighted from their fear; by this we moderate excessive joy; by this we assuage the passions of lust and anger.

This it is which bound men by the chains of right and law, formed the bonds of civil society, and made us quit a wild and savage life.
And it will appear incredible, unless you carefully observe the facts, how complete the work of nature is in giving us the use of speech; for, first of all, there is an artery from the lungs to the bottom of the mouth, through which the voice, having its original principle in the mind, is transmitted.

Then the tongue is placed in the mouth, bounded by the teeth.

It softens and modulates the voice, which would otherwise be confusedly uttered; and, by pushing it to the teeth and other parts of the mouth, makes the sound distinct and articulate.

We Stoics, therefore, compare the tongue to the bow of an instrument, the teeth to the strings, and the nostrils to the sounding-board.
LX.