Environment changes, and religions, laws, and social institutions change with it. Empires rise and fall, old civilizations disappear, old creeds become incredible, and often, for a time, the course of humanity seems to be retrograde. But as the flowing tide rises, though the successive waves on the shore advance and recede, evolution, or the law of progress, in the long run prevails, and amidst the many oscillations of temporary conditions, carries the human race ever upwards towards higher things. In the case of ancient religions it is easy to see how this process of degeneration is carried out. Priests who were the pioneers of progress, and leaders of advanced thought, became first conservatives, and then obscurantists. Pantheistic conceptions, and personifications of divine attributes, lead to polytheism. As religions become popular, and pass from the learned few to the ignorant many, they become vulgarized, and the real meaning of myths and symbols is either lost or confined to a select inner circle. But for my present purpose, which is mainly chronological, these vicissitudes in religious beliefs are not important. If, at the earliest date to which authentic history extends, we find a national religion which has already passed from the primitive into the metaphysical stage, and which embodies abstract ideas, astronomical observations, and a high and pure code of morals, it is a legitimate inference that it is the outcome of a long antecedent era of civilization. This is eminently the case with regard to the ancient religions of Egypt and Chaldæa. The ancient Egyptians were the most religious people ever known. Their thoughts were so fixed on a future life that, as Herodotus says, they looked upon their houses as mere temporary inns, and their tombs as their true permanent homes. The idea of an immediate day of judgment for each individual soul after death was so fixed in their minds that it exercised a constant practical influence on their life and conduct. Piety to the gods, loyalty to the throne, obedience to superiors, justice and mercy to inferiors, and observance of all the principal moral laws, and especially that of truthfulness, were enforced by the conviction that no sooner had the breath departed from the body, and it had been deposited as a mummy, with its Ka or second shadowy self, in the tomb, than the soul would have to appear before the supreme judge Osiris, and the forty-two heavenly jurors, where it would have to confess the naked truth, and be tried and rewarded or punished according to its merits. It is very interesting, therefore, to learn what the religion was which had taken such a firm hold of the minds of an entire nation, and which maintained that hold for the best part of 5000 years. [Illustration: JUDGMENT OF THE SOUL BY OSIRIS.--WEIGHING GOOD AND BAD DEEDS. (From Champollion's _Egypt_.)]