The Book of Isaiah is written by the prophet Isaiah, whose name means "salvation of the Lord." The plan of salvation is the underlying theme of his book, which is almost 60% prophecy. It was written int he 8th Century B.C. and the key verse, taken from 12:2, is "Behold, God is my salvation; I will trust, and not be afraid: for the LORD JEHOVAH is my strength and my song; he also is become my salvation."