Quotation from: The Chessmen of Mars

Written by: Edgar Rice Burroughs

"There be none nobler," replied Lan-O. "In Manatos none but
wicked criminals who deserve death are forced to play at jetan,
and even then the play is fair and they have their chance for
freedom. Volunteers may play, but the moves are not necessarily
to the death--a wound, and even sometimes points in swordplay,
deciding the issue. There they look upon jetan as a martial
sport--here it is but butchery. And U-Thor is opposed to the
ancient slave raids and to the policy that keeps Manator forever
isolated from the other nations of Barsoom; but U-Thor is not
jeddak and so there is no change."