k 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.]

The ancient Mexicans had not arrived at this stage, which in the Old
World characterized the upper period of barbarism. Slavery had, however,
made a beginning among the Aztecs. The nucleus of the small
slave-population of Mexico consisted of _outcasts_, persons expelled
from the clan for some misdemeanour. The simplest case was that in which
a member of a clan failed for two years to cultivate his
garden-plot.[134] The delinquent member was deprived, not only of his
right of user, but of all his rights as a clansman, and the only way to
escape starvation was to work upon some other lot, either in his own or
in some other clan, and be paid in su