He who is not self-restrained has no steadiness of mind; nor has he who is not self-restrained perseverance in the pursuit of self-knowledge; there is no tranquillity for him who does not persevere in the pursuit of self-knowledge; and whence can there be happiness for one who is not tranquil? For the heart which follows the rambling senses leads away his judgment, as the wind leads a boat astray upon the waters.