[Footnote 133: The victim, by the offer of which the wrath of the god was appeased or his favour solicited, must always be some valued possession of the sacrificer. Hence, e. g., among the Hebrews "wild animals, as not being property, were generally considered unfit for sacrifice." (Mackay, _op. cit._ ii. 398.) Among the Aztecs (Prescott, _loc. cit._) on certain occasions of peculiar solemnity the clan offered some of its own members, usually children. In the lack of prisoners such offerings would more often be necessary, hence one powerful incentive to war. The use of prisoners to buy the god's favour was to some extent a substitute for the use of the clan's own members, and at a later stage the use of domestic animals was a further substitution. The legend of Abraham and Isaac (_Genesis_, xxii. 1-14) preserves the tradition of this latter substitution among the ancient Hebrews. Compare the Boeotian legend of the temple of Dionysos Aigobolos:--[Greek: thyontes gar to theo proechthesan pote hypo methes es hybrin, hoste kai tou Dionysou ton hierea apokteinousin; apokteinantas de autika epelabe nosos loimodes; kai sphisin aphiketo hama ek Delphon, to Dionyso thyein paida horaion; etesi de ou pollois hysteron ton theon phasin aiga hiereion hypallaxai sphisin anti tou paidos.] Pausanias, ix. 8. A further stage of progress was the substitution of a mere inanimate symbol for a living victim, whether human or brute, as shown in the old Roman custom of appeasing "Father Tiber" once a year by the ceremony of drowning a lot of dolls in that river. Of this significant rite Mommsen aptly observes, "Die Ideen goettlicher Gnade und Versoehnbarkeit sind hier ununterscheidbar gemischt mit der frommen Schlauigkeit, welche es versucht den gefaehrlichen Herrn durch scheinhafte Befriedigung zu beruecken und abzufinden." _Roemische Geschichte_, 4e Aufl., 1865, Bd. i. p. 176. After reading such a remark it may seem odd to find the writer, in a footnote, refusing to accept the true explanation of the custom; but that was a quarter of a century ago, when much less was known about ancient society than now.] [Sidenote: Aztec slaves.]