53. PREFACE - Only after having passed through the tests offered by physical life can Spirits reach perfection. Those who are in an errant state await God's permission to return to an existence which can offer them progress, either by the expiation of their faults by means of the vicissitudes to which they will be subjected, or by the undertaking of a mission which will benefit humanity. Their advancement and future happiness will be in proportion to the manner in which they employ the time given to them on Earth. The duty of guiding their first steps and of leading them towards goodness is up to their parents, who will have to give an account to God for the degree of fulfilment they gave to this mandate. It was to help them that God made paternal and filial love a Law of Nature, a law which can never be transgressed with impunity.