Asvaghosha - The Awakening of Faith in the Mahayana - The reason for reincarnation
Type of Spiritual Experience
One reincarnates - goes round the cycle of birth and death again and again - because one has not found enlightenment.
One reason why we don't become enlightened is because we take too much notice of the external world.
If we can detach ourselves from the perceptions we are getting of the outside world and become immune to them, then we are on the way to enlightenment - at least partly.
Note that there is much more to enlightenment than understanding that what we perceive is not Reality, but by doing so one is less likely to form erroneous beliefs and this has a very positive impact.
A description of the experience
Asvaghosha - The Awakening of Faith in the Mahayana translated by D T Suzuki
Birth-and-death has its raison d’etre and its cause. Non-enlightenment is the raison d'etre, and the external world as produced by subjectivity is the condition.
When the raison d'etre is removed, the condition is removed. When the condition is removed, the state of an interrelated mind is removed. When the raison d'etre is removed, the state of a non-interrelated mind is removed.
It may be asked: If the mind be removed, how can there be mentation? If mentation really occurs, how can there be removal?
In reply we say that while the objection is well founded; we understand by the removal, not that of the mind itself, but of its modes.