As in a dream the Soul plays as if invested with a body which, of course, is due to the action of the mind, similarly, it gets in the mother's womb a body in consequence of qualities and propensities created by pristine deeds.
रमत्ययं यथा स्वप्ने मनसा देहवानिव। कर्मग:गुणैर्देही गर्भे तदुपलभ्यते॥