"When the Sun is in the first part of the lunar mansion Krittika, and the Moon in the fourth of Vishakha; or when the Sun is in the third part of Vishakha, and the Moon is in the head of Krittika (these positions being contemporary with the equinoxes), that equinoctial season is holy and is styled the Mahavishubha, or great equinox (VP VIII.71- 3)."