In his explanation, Gabriel traverses the entire vision, explaining in part the various symbols, and finishes with the assurance that the 2300 days is the correct measure of it all.
Daniel, who was thinking specially of Israel, and of the fulfilment of God's promises to the fathers, perceived that all that he had heard could not occur in 2300 literal days, especially when Gabriel said to him, "But shut thou up the vision, for it will be fulfilled after many days." And though he knew not how long each symbolic day would be, he was made sick at heart by the thought of so many evils as were coming upon God's people--though he saw not the change of that name from fleshly to spiritual Israel. We read, "And
I, Daniel, languished and was sick for some days"; and "I was astonished at the vision, but none could interpret it." And well it was for Daniel, and for all God's children from then to the Time of the End, that the dread significance of that vision of papal power and persecution, and of saintly suffering, was not more clearly revealed in advance. Our merciful Heavenly Father, while willing to prove his people in the furnace of affliction and persecution, in order to prepare a people for the exceeding and eternal weight of glory promised, deals with us upon the principle--"Sufficient unto the day is the evil thereof."
Daniel, who was more interested in Israel than in the Persian "ram," or the Grecian "goat," knew from Jeremiah's prophecy that the seventy years of captivity in Babylon was a punishment upon Israel for sins, and so now he judged from the vision of coming persecutions (instead of exaltation and glory as he had expected) that it betokened Israel's sin and God's wrath; hence he prayed earnestly for forgiveness of Israel's sins, and for the fulfilment of the promises made to the fathers. This is told in few words in Dan. 9:2-19. Daniel saw not the scope of the divine plan as we may now behold it; nevertheless, his earnestness and faith in the promises were pleasing to God, who therefore revealed to him something more concerning this vision--an increase or further elaboration of it, in those features which specially pertained to fleshly Israel. Daniel supposed that the end of the seventy years' desolation of the land of Israel, while its people were in Babylon, was to be thus prolonged, or continued, for many (2300) days. God corrects this error by sending Gabriel to inform him that the captivity would end when the seventy years were complete, and that the city of Jerusalem and the temple would be rebuilt, though in a troublous period, etc.
It was while Daniel was praying over the vision of the 2300 days, which he misunderstood to mean a prolonging
of the 70 years captivity in Babylon, that Gabriel was sent to further explain that misunderstood vision, thus (Dan. 9:21-27):
"And he talked with me and instructed me, and said, O Daniel, I am now come forth to teach thee, that thou mayest understand. From the beginning of thy prayers the [further] declaration [of God's plan, now to be communicated] went forth, and I am come to tell it; for thou art greatly beloved: therefore understand this [further] matter, and have understanding of the vision [of the 2300 days]. Seventy weeks [70 x 7 = 490 days] are cut off [or set apart, fixed, or determined] upon thy people [Israel] and upon thy holy city [Jerusalem]," etc.