That state should be understood to be called Yoga, in which there is a complete severance of all connection with pain. Such Yoga should be practised with steadiness, and with an undisponding heart.
तं विद्याद् दुःखसंयोगवियोगं योगसंज्ञितम्। स निश्चयेन योक्तव्यो योगोऽनिर्विण्णचेतसा॥