In classical Advaita (Non-Dual) Vedanta, there are three main theories or viewpoints of reality, called shristi-dristi vada, dristi-shristi vada and lastly ajata vada. Whilst these Sanskrit words may appear complex, the idea is actually very simple, and Bhagavan Sri Ramana Maharshi explains the meaning of these terms below.
It may be helpful to note that ‘vada’ means ‘theory’ or ‘viewpoint’, ‘shristi’ means ‘the world’ or ‘creation’, ‘dristi’ literally means ‘sight’ but in this context refers to consciousness, and ‘jata’ means ‘birth’. Adding ‘a’ as a prefix to ‘jata’ negates the meaning so that ‘ajata’ means ‘unborn’.
Therefore shristi-dristi vada is the view that the world is primary and gives rise to consciousness, dristi-shristi vada is the view that consciousness is primary and gives rise to the world appearance, and ajata vada is the view that there never was any creation at all, and that there is only The Absolute.
To explain further, here is an excerpt from Day by Day with Bhagavan from 15th March, 1946:
[Ramana Maharshi:] I do not teach only the ajata doctrine. I approve of all schools. The same truth has to be expressed in different ways to suit the capacity of the hearer. The ajata doctrine says, “Nothing exists except the one reality. There is no birth or death, no projection or drawing in [of the world], no sadhaka [no seeker], no mumukshu [no one seeking liberation], no mukta [no liberated person], no bondage, no liberation. The one unity alone exists ever.”
‘To such as find it difficult to grasp this truth and who ask. “How can we ignore this solid world we see all around us?” the dream experience is pointed out and they are told, “All that you see depends on the seer. Apart from the seer, there is no seen.”
‘This is called the drishti-srishti vada, or the argument that one first creates out of his mind and then sees what his mind itself has created.
‘To such as cannot grasp even this and who further argue, “The dream experience is so short, while the world always exists. The dream experience was limited to me. But the world is felt and seen not only by me, but by so many, and we cannot call such a world non-existent,” the argument called srishti-drishti vada is addressed and they are told, “God first created such and such a thing, out of such and such an element and then something else, and so forth.” That alone will satisfy this class. Their mind is otherwise not satisfied and they ask themselves, “How can all geography, all maps, all sciences, stars, planets and the rules governing or relating to them and all knowledge be totally untrue?” To such it is best to say, “Yes. God created all this and so you see it.”’
Dr. M. said, ‘But all these cannot be true; only one doctrine can be true.’
Bhagavan said, ‘All these are only to suit the capacity of the learner. The absolute can only be one.’
In Guru Vackaka Kovai (Garland of Guru’s Sayings), Ramana says the following (with a comment by Sri Sahdu Om):
100. Although Guru Ramana taught various doctrines according to the level of understanding of those who came to Him, we heard from Him that ‘Ajata’ alone is truly His own experience. Thus should you know.
Sri Sadhu Om: ‘Ajata’ is the knowledge that nothing – neither the world, soul nor God – ever comes into existence, and that ‘That Which Is’ ever exists as IT is.
114. When the limited light [which is used to project pictures on the cinema screen] is dissolved in the bright sunlight [which enters the cinema], the pictures also will disappear instantaneously. Similarly, when the limited consciousness [chittam] of the mind is dissolved in supreme Consciousness [Chit], the picture show of these three prime entities [God, world and soul] will also disappear.
115. Thus, since the Truth of the Source is One, why do all religions [and sometimes even Sages] start their teachings by at first conceding that these three prime entities are real? Because the mind, which is tossed about by objective knowledge, would not agree to believe in the One unless the Sages condescended to teach It as three.
122. Whatever high and wonderful state of tapas one may have attained, if one still identifies oneself with an individuality, one cannot be a Sahaja-Jnani [i.e. One in the State of Effortlessness]; one is only an aspirant of, perhaps, an advanced stage.
Also see Ramana Maharshi: how to abide as the Self, the world is not real, attend to yourself