As has been mentioned, Isaiah, the son of Amoz, was a member of the royal family. He made his first public appearance as the Divinely inspired prophet in the year of Uzziah's affliction with leprosy, and he ministered to the people for about ninety years, during the reigns of kings Uzziah, Jotham, Ahaz, and Hezekiah.
Isaiah had seen the growth of a new empire, Assyria, and the fall of the Northern Kingdom of Israel. Judea alone remained, and it was the last bulwark of the true faith in One G‑d. Isaiah brought to king and people the message of the holiness of G‑d, the L-rd of hosts, at a time when idolatry seemed to be taking hold in the land of Judah. He preached justice and charity at a time when the morals of the people had reached a new low. Of his Divine call Isaiah tells as follows;
"In the year of King Uzziah's death (meaning, when he was stricken with leprosy and was isolated), I saw the L-rd sitting upon a high and exalted throne, and his train filled the Temple. Seraphim were standing around him. Each one had six wings; with two he covered his face, with two he covered his feet, and with two did he fly. And one called unto the other, and said: 'Holy, Holy, Holy is the L-rd of Hosts; the whole earth is full of His glory.' And the posts of the threshold shook at the voices of those that called aloud, and the house was filled with smoke. And I said: 'Woe is me, for I am lost, because a man of unclean lips am I, and in the midst of people of unclean lips do I dwell; for the King, the L-rd of Hosts, have mine eyes seen.' Then flew one of the Seraphim to me, and in his hand was a live coal he had taken from the altar with the tongs. And he laid it upon my mouth and said; 'Lo, this has touched thy lips, and thy iniquity is departed and thy sin is forgiven!'
"And I heard the voice of G‑d, saying: 'Whom shall I send, and who will go for us?' And I said: 'Here am I; send me.' And He replied: 'Go, say unto this people; Ye hear indeed, but understand not; ye see indeed, but know not. Made obstinate is the heart of this people; their ears are heavy and their eyes shut; or else their eyes would see, their ears hear, and their hearts be understanding, in order that they repent and be healed.' And I said: 'How long, oh L-rd?' And He replied: 'Until cities be left waste without inhabitants, and houses without men, and the land be made desolate as a wilderness. Till G‑d will have removed the men far away, and there will be great desolation in the midst of the land. And should a tenth part thereof remain, it will again be swept away. Yet like the terebinth and oak, which when felled, retain their roots and stem, so remains the stem of their holy seed.'"
Isaiah's mission was not only to admonish the people to keep them on the right path. He also instilled fervent faith in G‑d in the hearts of his flock, and he brought them courage and fortitude at a time when they were suffering mortal fear from the threat of the new Assyrian Empire. Isaiah also described in glowing terms the future glory of Zion, which inspires our people to the present day.