Bhavaṅga is a Pali word in the Abhidhamma texts of early Theravada Buddhism, describing a passive mode of consciousness.
It means the “ground or basis for becoming” or the “necessary condition for existence”.
It is the state in which the mind rests when there is no active or proactive consciousness.
It can be a state of mind when nothing appears to be going on, such as when one is in a state of deep dreamless sleep.
Also, in dreams and waking life, it momentarily fills the gap between each moment of active or proactive consciousness.
It is also the subconscious state when one is daydreaming or doing something according to habit or as a reflex or instinctive response.
But it is not Nothing.
Nor is it empty. It can be a storehouse of past or imagined experiences with, potentially, direct access to the Past or (imagined) Future.
It therefore forms part of the continuum of cause and effect (karma) which makes up one’s life.
We may interpret its continuance throughout life as the natural mode to which the mind continually reverts and seems to indicate the mind’s continuity.
Its tendency to repetitiveness can be interpreted as the characteristics of a “person” and reinforce notions of a self or identity.
In reality, there is only a flux of being. This appears to reveal characteristic features and tendencies of an individual. But only within the context of the extremities of a birth and a death. There is no permanent enduring Self.
Importantly, it is also a mental process which can condition the next mental process in the moments of death and rebirth.
Thus bhavanga can be a condition for the arising of cognitive awareness.
A “new” being’s first moment of bhavaṅga (re-linking consciousness) can also be directly conditioned by the last fully conscious process of the immediately preceding life, a state of “falling away” or “death consciousness.”
Hence, this concept helps provide an indication of psychological continuity.
Moreover, the last conscious or subconscious moment before death may operate as a kind of summing up of that life. Whatever seems to have been most significant in that life will tend to surface before the mind.
What comes before the subconscious mind at this point will play the principal role in determining the nature of the subsequent rebirth by way of Karma, Cause and Effect.
It is for this reason that in many religions, including Buddhism and some forms of Christianity, a monk or priest attends a dying man and encourages him to actively call to mind the good deeds he has done or his Saviour, if he has one. Or say prayers etc.
In the absence of one’s being able to do this, the subconscious Bhavaṅga, with all its unpredictableness, will be the determining factor.
Is that what you would want? Who can normally predict when, where or how he will die?
Would it not be better to be “up to date and ready to go”?
Knowing that one is on the “right train” and prepared for its “destination”.
Or, even, having experienced that destination and reviewed it in advance?