The meaning is, I believe, that in the human soul there is a better and also a worse principle; and when the better has the worse under control, then a man is said to be master of himself; and this is a term of praise: but when, owing to evil education or association, the better principle, which is also the smaller, is overwhelmed by the greater mass of the worse—in this case he is blamed and is called the slave of self and unprincipled.