Any rational justification of the hope for permanent peace must depend on our view of the causes of wars. It is equally obvious that no action for the promotion of peace can be effective unless it is based on a correct understanding of the causation, just as one cannot cure anyone without a proper diagnosis. The seventeenth-century Dutch jurist Hugo Grotius was the first writer to envisage the possibility that one day mankind might live without war. The years since the Second World War constitute a new era in the history of mankind: for the first time nobody praises war and everybody professes to love peace while even aggressors disguise their attacks as defence. The military hierarchy is usually so arranged that power and exposure to dangers and privations are inversely related, so that the commanders are able to push the underlings into battle while remaining safely behind.