The characteristic attitude of Isaiah is one of awe before the majesty of Yahwe, and fearless denunciation of ... the disobedience to Jahwe's moral commands, the attempt to placate Him by sacrifice and temple worship, the dependence upon warlike preparations and political alliances rather than on Yahwe, and the lack of faith in His safe guidance. He was convinced that the mass of the people because of its infidelity would go under, and that only a remnant would turn to their God after severe affliction. So far as the people at large was concerned, he cherished no illusions as to the effect of his oracles. . . . But he deposited his faithful testimony in the hearts of his disciples, and to this unknown circle of believers we probably owe the preservation of his prophecies. The terseness and vigor of his style, his command of all the resources of the language, his mastery of invective, sarcasm, and irony, the impetuousness of his speech, the grandeur and sublimity of his conceptions, and his uncompromising emphasis on the ethical demands, mark him as an extraordinarily gifted, powerful, and enlightened personality, as perhaps the greatest of all the Hebrew prophets.
—From the New International Encyclopædia
