The change from "we" to "ye" is very simple. "We," Peter and all, possess the word of prophecy; the "ye" applies to those he was exhorting. The mystery is not in the passage at all; but the "word of prophecy" is here in contrast, not directly with the mystery (though that connects itself with this), but with the day-star and the day dawning. Prophecy is a light in a dark place, this world; and refers to the events happening in this world and the judgment. And it is very well, as regards this world, to take heed to it. When the day is come, it will be Christ revealed, judgment on the world (compare Mal. 4) and resulting blessing. But there is a better hope for those who watch, and in contrast with judgment: the dawn and the star not seen by those who only appear when the sun is risen, but for saints who look for Christ before He appears, not warned merely and detached from earth, but associated in heart with Christ in heaven.
There is only a shade of meaning different in ὁ ἀστήρ ὁ πρωἴνός, Rev. 2:2828And I will give him the morning star. (Revelation 2:28), and φωσφόρος here, one referring to the early appearance, the other to its introducing dawn or light. Peter is speaking of prophecy as a light, a candle shining in a dark place—God's light in the darkness of this world; with which he contrasts Christ's heavenly coming, the hope of the saints as bringing in the light of a new day. ‘Ο ἀστὴρ ὁ πρωἴνός is merely what it is—its appellative, Christ Himself, still not in the kingdom: that precedes in verse 27, and is found rather in "the Root and Offspring of David" in chapter 22.
[1867]