Light of Self (Atman, Brahman, Absolute Reality, Being, Truth) is eternally covered with Ignorance (Avidya), which does not allow the Light to be appreciated. The Ignorance has no beginning, but has an end (in Realization).
It is darkness all around. In this state we see the Supreme Being as faint shadows - multifarious parts - as sentient or insentient beings.
The question of interest is: "Does this ignorance wane of gradually in degrees, or does is disappear in one stroke, as a 'all or none phenomenon?
To explain, can we say that spiritual practices (disciplines like listening to the words of Guru, reading the Scriptures, Yoga, worship, experiences of past births, etc.) lead to gradual thinning of this thick blanket of Ignorance that prevents us to realize the hidden Light?
Or, is it that the Darkness of Ignorance vanishes in a moment as when a candle is lighted in the room? It is then inconsequential whether the room was in the dark for a thousand years or for a day!