26. Incarnation is not then normally a punishment for the spirit, as some have thought it, but an inherent condition and a means of progress (“Heaven and Hell,” by Allan Kardec, chap. III, from item n° 8 on).
By measure, as the spirit progresses morally, he dematerializes himself; that is to say, that preserving himself from the influence of matter, he purifies himself, his life becomes spiritualized, his faculties and perceptions are extended, his happiness is by reason of accomplished progress. But, as he acts by virtue of his free will, he can, by negligence or bad desire, hold up his advancement. He prolongs, therefore, the duration of his material incarnations, which become then for him a punishment, since by his own fault he remains in the inferior ranks, obliged to recommence the same task. It depends then upon the spirit to abridge by its work of self-purification the duration of the period of its incarnations.