The senses are the horses and the roads they travel are the mazes of desire. When a man lacks discrimination and his mind is uncontrolled, his senses are unmanageable like the restive horses of a charioteer. But when a man has discrimination and his mind is controlled, his senses, like the well-broken horses of a charioteer, lightly obey the rein. (Katha Upanishad)
There are two ways, one of the worldly pleasure and the other of bliss. Of these two, those who take up the good are blessed, whole those who take to the evil, do not attain success. (Katha Upanishad)
An intelligent man should suppress his speech and his mind. (Kena Upanishad)
They who neglect their social duties for their individual life fall in darkness; and those who sacrifice their individuality for social popularity fall into greater darkness. (Isha Upanishad)