To paraphrase a recent author "perhaps we foresee a time when men, exultant in the technique of homicide, will rage so hotly over the world that every precious thing will be in danger, every book and picture and harmony, every treasure garnered through two millenniums, the small, the delicate, the defenseless—all will be lost or wrecked or utterly destroyed." what technique is roosevelt primarily using to refute the belief that america should remain isolated?