The subject, the consciousness, receives objects from
within and without. When a person is in a state of profound
sleep his mind is said to be vacant, or, in other
words, in a state of Bhavaïga. We always experience such
a passive state when our minds do not respond to external
objects. This flow of Bhavaïga is interrupted when objects
enter the mind. Then the Bhavaïga consciousness
vibrates for one thought-moment and passes away.