Whether it was originally of Divine origin, or whether it was only an instinctive expression, now of the gratitude, and now of the guilt and fear, of the human heart, we are not told. Nor is the basal idea on which it was founded ever explained to us. Were the ideas of "atonement" or propitiation (_Kippurim_) really connected with those of substitution and vicarious punishment? Or was the main conception that of _self_-sacrifice, which was certainly most prominent in the burnt offerings? Doubtless the views alike of priests and worshippers were to a great extent indefinite. We are not told what led Cain and Abel to present their sacrifices to God; nor did Moses--if he were its founder--furnish any theories to explain the elaborate system laid down in the Book of Leviticus. The large majority of the Jews probably sacrificed simply because to do so had become a part of their religious observances, and because in doing so they believed themselves to be obeying a Divine command. Others, doubtless, had as many divergent theories as Christians have when they attempt to explain the Atonement. The "_substitution_" theory of the "sin offering" finds little or no support from the Old Testament; not only is it never stated, but there is not a single clear allusion to it. It is emphatically asserted by later Jewish authorities, such as Rashi, Aben Ezra, Moses ben-Nachman, and Maimonides, and is enshrined in the Jewish liturgy. Yet Dr. Edersheim writes: "The common idea that the burning, either of part or the whole of the sacrifice, pointed to its destruction, and symbolised the wrath of God and the punishment due to sin, does not seem to accord with the statements of Scripture."[329] Sacrifices were of two kinds, bloody (_Zebach_; LXX., θυσία), or unbloody (_minchah_, _korban_; LXX., δῶρον, προσφορά). The latter were oblations. Such were the cakes of shewbread, the meal and drink offerings, the first sheaf at Passover, the two loaves at Pentecost. In almost every instance the _minchah_ accompanied the offering of a sacrificial victim. The two general rules about all victims for sacrifice were, (1) that they should be without blemish and without spot, as types of perfectness; and (2) that every sacrifice should be salted with salt, as an antiseptic, and therefore a type of incorruption.[330] Sacrificial victims could only be chosen from oxen, sheep, goats, turtle doves, and young pigeons--the latter being the offering of the poor who could not afford the costlier victims.