Why does the human being not remember his former incarnations? Put like this, this question makes little sense. You will understand in a moment why I say this. It is as if someone says: ‘human beings call themselves human beings; in front of us stands a four-year-old child that can’t count’. Then he continues to say: ‘this child cannot count, however if it is a human being so that means humans cannot count.’ It is, however, a matter of development. At some stage in life every person will come to a point which advanced students have already reached, namely the ability to recall past lives; If he cannot remember anything, then he has to acquire this skill first just like the child acquires the skill of reading, doing arithmetic and writing. The person must not unconsciously let destiny pass him by if he intends to let his experiences lead him towards the point where he can remember earlier lives on earth.
Source (German): Rudolf Steiner – GA 054 – Berlijn, Die Welträtsel und die Anthroposophie – February 15, 1906 (page 300)
Translated by Nesta Carsten-Krüger