Ramana Maharshi on thirst for Life and Rebirth

Question : What is the cause of tanha, the thirst for life and the thirst for rebirth?
Ramana Maharshi : Real rebirth is dying from the ego into the spirit. This is the significance of the crucifixion of Jesus. Whenever identification with the body exists, a body is always available, whether this or any other one, till the body-sense disappears by merging into the source - the spirit, or Self. The stone which is projected upwards remains in constant motion till it returns to its source, the earth, and rests. Headache continues to give trouble, till the preheadache state is regained.

Thirst for life is inherent in the very nature of life, which is absolute existence - sat. Although indestructible by nature, by false identification with its destructible instrument, the body, consciousness imbibes a false apprehension of its destructibility. Because of that false identification it tries to perpetuate the body, and that results in a succession of births. But however long these bodies may last, they eventually come to an end and yield to the Self, which alone eternally exists.