This recognition of a community of interests engenders among the members of the group a sentiment of unity and fraternal solidarity which constitutes its real strength. The laws of such a group can determine to what extent the individual must forfeit his personal freedom, the right of using personal force as an instrument of violence, to ensure the safety of the group. But such a combination is only theoretically possible; in practice the situation is always complicated by the fact that, from the outset, the group includes elements of unequal power, men and women, elders and children, and as a result of war and conquest, victors and the vanquished—that is masters and slaves—as well. Moreover, all forms of war cannot be indiscriminately condemned; so long as there are nations and empires, each prepared callously to exterminate its rival; all alike must be equipped for war.