Beside the faded colours of the mythology, the decreasing importance of animal sacrifice, and the formalism of the prayers, we observe in the five Gathas, the invocations which alone have preserved the verse-measure, and present older forms of language than the rest, a tendency to speculation. Not only are the good and evil spirits combined under one head, as is always the case in the Avesta, but the Gathas attempt to resolve the contrast of the beneficial and harmful sides of nature, of the good and evil spirits, into the reciprocal play of two fundamental forces; they identify the prosperity and destruction of nature with moral good and evil, and combine the one with truth, the other with falsehood. The good spirits are the truth, the evil are the lie. The life of appearance and of falsehood is distinguished from the true life, and the service of truth promises life not in this world only but in the next. It is in harmony with these tendencies to abstraction that, according to other passages of the Avesta, heaven is filled with a multitude of the most lifeless personifications of ideas and realities. Could the doctrine of a new religion in an early period come forward with such a spiritualised system, with such elevated moral demands, such abstract conceptions? Could prayers of such a kind have been composed or written down in a primitive age? The existing fragment of the book of the law is composed in the form of a dialogue, and is for the most part filled with conversations which Zarathrustra carries on with Auramazda. Zarathrustra inquires what is to be done in certain cases against the evil spirits, the Daevas, on the commission of certain sins and impurities. What must be done when a woman is in labour, etc., or when any one has made himself impure by touching a corpse, or has slain a water-dog (otter)? Is the rain impure which has fallen on a corpse and then runs off from it, etc.? These questions Auramazda answers very precisely, and when it is a matter for expiation and purification, he fixes the number of stripes with the horse-whip or the whip of the sacred Çraosha (Çraosha-charana) which the penitent is to receive. It is a theory and practice of purity, on a level with the analogous rules in the laws of Manu, and in some points even more subtle and casuistical. The offences have already been brought under definite categories, and in like manner the purifications and punishments fall into a number of distinct classes. Not only are expiations required for all sins and prescribed down to the minutest details, but the offences must also be repented of; certain formulæ of confession and repentance are prescribed.