And the glory of the LORD shall be revealed, and all flesh shall see it together: for the mouth of the LORD has spoken it.
Read Chapter 40
Ambrose of Milan
He [Christ] was a reproach but at the same time also the majesty of the Lord, as it is written, “And the glory of the Lord shall be revealed, and all flesh together shall see the salvation of God.” What had he lost if he had nothing less? He had neither comeliness nor beauty, but he had not ceased to be the power of God. He appeared a man, but the divine majesty and glory of the Father shone on earth. - "Letter 27"
And this is the Lord of glory, and we too have come to know his glory. However, those of old did not see it when he showed himself during the dispensation in which he was made man, equal to God the Father in strength, operation and glory, bearing all things by the word of his power and with great tranquillity performing godly works, enhancing creation, raising the dead and performing other deeds of wonder effortlessly. For the glory of the Lord appeared, and all flesh saw the salvation of God, that is, of the Father. For he has sent us his Son from heaven to salvation and redemption. For the law brings no one to perfection, for the sacrifices in prefigurative form were unable to deal with sin. But we have been perfected in Christ and reconciled from every fault as we have been honored with the spirit of sonship. - "Commentary on Isaiah 22.214.171.124–5"
But when he took on flesh, he took on the universal logos of flesh. For he triumphed over the powers of all flesh in the flesh, and thus he came to the aid of all flesh, as is said in Isaiah, “all flesh will see the salvation of God,” and in the psalms, “All flesh will come to you.” - "Against Arius 3.3"
All flesh, that is, every man can not see the salvation of God in Christ in this life. The Prophet therefore stretches his eye beyond to the last day of judgment, when all men both the elect and the reprobate shall equally see Him.