The spiritual religion promulgated at Sinai did not intend sacrifices as the expression of divine adoration, but was meant to inculcate a moral and holy life; the people, however, had not yet risen to this conception, and could only be advanced by means of education and culture. The other ancient nations having found in sacrifices the means of propitiating their deities, the Israelites were permitted to retain the same mode of divine service; but its form was simplified. The altar became an integral part of the sanctuary, in which no image was tolerated. The only objects contained therein were a candelabrum, a table with twelve loaves, symbolising the twelve tribes; and there was also a recess for the Ark of the Covenant. Altar, sanctuary and sacrificial rites required a priesthood. This primæval institution, too, was retained. The Levites, as the most devoted and best informed tribe, were charged with sacerdotal functions, as during the sojourn in Egypt. The priests of Israel, unlike those of the Egyptians, were precluded from holding landed property, as such possessions might have tempted them to misuse their prerogatives and neglect their sacred duties. For this reason it was prescribed that their subsistence should be derived from the offerings made by the people. Collaterally there existed a custom, dating from remote patriarchal ages, which demanded that the first-born son of every family should attend to the performance of sacrificial rites. This prerogative could not be abruptly abolished, and continued for some time alongside of the Levitical priesthood, though both of them stood in the way of the pure Sinaitic teachings. The materialism of the age demanded indulgent concessions, combined with provisions tending to the refinement of popular habits. Only through the aid of the spiritually gifted could the understanding of the subordinate nature of sacrifices be preserved in the consciousness of the people. During the forty years of their wandering in the desert, the Israelites sought pastures for their flocks within the mountain region and its neighborhood. During these migrations Moses instructed the people. The older generation gradually passed away. Their descendants, obedient to the teachings of the lawgiver and his disciples, formed a docile, pious, and valiant community, and became proficient in the knowledge of their laws.