In Isaiah's day idolatry itself no longer provoked surprise. Iniquitous practices had become so prevalent among all classes, that the few who remained true to God were often tempted to lose heart, and to give way to discouragement and despair.... TA 135.1
Such thoughts as these were crowding through Isaiah's mind as he stood under the portico of the temple. Suddenly the gate and the inner veil of the temple seemed to be uplifted or withdrawn, and he was permitted to gaze within, upon the holy of holies, where even the prophet's feet might not enter. There rose up before him a vision of Jehovah sitting upon a throne high and lifted up, while the train of His glory filled the temple. On each side of the throne hovered the seraphim, their faces veiled in adoration, as they ministered before their Maker, and united in the solemn invocation, “Holy, holy, holy, is the Lord of hosts: the whole earth is full of His glory.”—Prophets and Kings, 306, 307. TA 135.2
An indescribable glory emanated from a personage on the throne, and His train filled the temple.... Cherubim were on either side of the mercy-seat, as guards round the great King, and they glowed with the glory that enshrouded them from the presence of God. As their songs of praise resounded in deep, earnest notes of adoration, the pillars of the gate trembled, as if shaken by an earthquake. These holy beings sang forth the praise and glory of God with lips unpolluted with sin. The contrast between the feeble praise which he [Isaiah] had been accustomed to bestow upon the Creator and the fervid praises of the seraphim, astonished and humiliated the prophet. He had for the time being, the sublime privilege of appreciating the spotless purity of Jehovah's exalted character. TA 135.3
While he listened to the song of the angels, as they cried, “Holy, holy, holy, is the Lord of hosts; the whole earth is full of his glory,” the glory, the infinite power, and the unsurpassed majesty of the Lord passed before his vision, and was impressed upon his soul. In the light of this matchless radiance, that made manifest all he could bear in the revelation of the divine character, his own inward defilement stood out before him with startling clearness. His very words seemed vile to him.—The Review and Herald, October 16, 1888. TA 136.1
The seraphim dwelt in the presence of Jesus, yet they vailed with their wings their faces and their feet. They looked upon the King in His beauty, and covered themselves. When Isaiah saw the glory of God, his soul was prostrated in the dust. Because of the unclouded vision he was graciously permitted to behold, he was filled with self-abasement. This will ever be the effect upon the human mind when the beams of the Sun of Righteousness shine gloriously upon the soul.... As the increasing glory of Christ is revealed, the human agent will see no glory in himself; for the concealed deformity of his soul is laid bare, and self-esteem and self-glorying are extinguished. Self dies, and Christ lives.—BE&The Signs of the Times, December 3, 1894. TA 136.2
Such was the prospect that greeted Isaiah when he was called to the prophetic mission; yet he was not discouraged, for ringing in his ears was the triumphal chorus of the angels surrounding the throne of God, “The whole earth is full of His glory.” Isaiah 6:3. And his faith was strengthened by visions of the glorious conquests by the church of God, when “the earth shall be full of the knowledge of the Lord, as the waters cover the sea.” Isaiah 11:9.—Prophets and Kings, 371. TA 137.1