[17] Slavery, then, is of two kinds; slavery of the soul and slavery of the body. Now, of our bodies, men are masters; but over our souls, wickedness and the passions have the dominion. And we may speak of freedom in the same manner. For one kind of freedom gives fearlessness of body in respect of any dangers which can come upon it from men of still more powerful body; while the other produces peace to the mind, by putting a check upon the authority of the passions.