Man is impelled by desire when he is descending to earthly incarnation. Not for nothing is desire for the Earth born in man. The end and aim is that he shall learn. We learn through all our experiences and they enrich our store of knowledge. But in order that man may learn on the Earth, he must be allured by, [or] involved in (physical) enjoyment.
When the soul is experiencing the past life in the astral world after death, in backward order, there must be abnegation of enjoyment, while the essence of the experience itself is retained. The passage through the astral world is thus a purification whereby the soul learns to forego all taste for physical pleasures.
Source: Rudolf Steiner – GA 94 – An Esoteric Cosmology – IX: The Astral World – Paris, 2nd June 1906
Translated by Rene Querido