The messenger who brought the word of the Lord to Lehi concerning the destruction of Jerusalem, and the commandment to leave the city, (1 Ne. 10:4), told him that the Messiah would come six hundred years from the exodus of himself and family. This is one of the few divine predictions on record in which a definite time is set for the fulfilment of a divine decree.
Another prophecy of that class is the word of the Lord delivered by the angel Gabriel to the Prophet Daniel in Babylon (Dan. 9:24-27). This is one of the grandest predictions on record. The angel Gabriel declares that seventy “weeks”—490 years—“are determined upon thy people and upon thy holy city, to finish”—or rather, to “restrain”—“the transgression,” etc. That is, in 490 years the Mosaic dispensation would come to an end. The chronology from this time is at best uncertain, but the following is worthy of consideration:
“That the seventy weeks mentioned by Daniel denote weeks of years is agreed by almost every commentator, but not the time when these seventy weeks, or 490 years, began. It is plain they began from an edict or warrant to build the city of Jerusalem, and not from an edict to rebuild the temple; they could not therefore begin at the edict of Cyrus, or Darius ... but at the edict of Artaxerxes Longimanus, ... either in the seventh year of his reign, when he gave Ezra his commission (Neh. 2). The edict in the seventh year ... appears to have been just 490 years before our Savior’s death, by which he finished transgression, and made an end of sin, by his complete atonement. Of these, seven weeks or forty-nine years, were spent in rebuilding the city and its walls and these ended about the [time of the] death of Nehemiah. Sixty-two more weeks, or 434 years, elapsed, before the ministry of John or Christ began.... Jesus, in the last half of the seventieth week, that is, at the end of it, made the sacrifice and oblation.” (The Popular and Critical Bible Encyclopedia, Dr. Samuel Fallows, Editor, Vol. 2, p. 1558.)
It was Gabriel who communicated this message to Daniel. The matter, he said, had been “determined.” (Dan. 9:24) Undoubtedly in a divine council meeting at which he had been present. There is no reason why we may not surmise that Gabriel perhaps was the angel who had visited Lehi, as he now visited Daniel. Lehi and Daniel were contemporary. But the latter, while still a young boy, was carried to Babylon. The vision in Chapter 9 is supposed to have been given in the year 538 B. C., in the first year of Darius the Mede.
A word of explanation may be called for here: Why read 490 “years” instead of seventy “weeks”? Why forty-nine “years” instead of seven “weeks”?
The answer is that the original text does not say seven “weeks,” or seventy “weeks,” but seven “sevenths,” and, seventy “sevenths.” The question, therefore, is, What does “sevenths,” not “weeks,” mean?
But the Jews had “sevens,” (i.e. weeks) of years as well as “sevens” (or weeks) of days; for, every seventh year was a Sabbath year, and every period of years from Sabbath to Sabbath was a “seven” (or “week”) of years. Now, inasmuch as the vision of Daniel was historical, necessarily referring to years and not to days, the “sevenths” mentioned must be “weeks” of years.