If we take into consideration the initial intuition (kensho) of our true nature which is also unconditioned, we can now distinguish between the unconditioned and the conditioned—between the essence of thought and thought. Before this critically important intuition we could not. We were only speculating and forming various ideas about the absolute. We were still immersed in avidya or primal ignorance inasmuch as we could not distinguish the unconditioned from the conditioned.
With awakening to our true nature, avidya comes to an end this being ‘sudden enlightenment’. Still, we are not perceiving the world the way a Buddha or Tathagata does. That will come much later owing to the problem of our long established habit of perceiving the world as ignorant beings. This is where gradual cultivation fits in. According to Zen master Heze Shenhui:
“All those who want to learn the Tao (Way) must achieve Sudden Enlightenment to be followed by Gradual Cultivation. It is like child-birth, which is a sudden affair, but the child will require a long process of nurture and education before he attains his full bodily and intellectual growth."
This long established habit is vāsāna which is why gradual cultivation is necessary.
Vāsāna, according to D.T. Suzuki in his Studies in the Lankavatara Sutra, “is morally evil and logically erroneous inasmuch as it creates an external world and causes us to cling to it as real and final.” I would add that vāsāna completely conceals how a Buddha perceives the world.
Even with kensho, vāsāna still dominates us, we fail to see the world the way a Buddha does. We are just low grade Bodhisattvas at this point.
The stages of a Bodhisattva are like way stations. They represent degrees of progress, this being how far we have integrated (samādhi) with our true nature coming to see the true world as vāsāna diminishes. Finally, after many years, we see the world as it is from a Buddha’s perspective which is unlike anything human. It is our former avidya perception flipped over to vidya with the vāsāna removed which are the old habits of perception (which sees only the conditioned). Put another way, as we integrate more and more with our true nature our former vāsāna looses its grip on us which kept us in avidya.