Matthew 17:3

3. There appeared… Moses and Elias Alford well remarks: “The two who appeared to them were the representatives of the law and the prophets; both had been removed from this world in a mysterious manner the one without death, the other by death indeed, but so that his body followed not the lot of the bodies of all; both, like the Greater One with whom they spoke, had endured that supernatural fast of forty days and nights; both had been on the holy mount in the visions of God. And now they came endowed with glorified bodies, before the rest of the dead, to hold converse with the Lord on that sublime event which had been the great central subject of all their teachings, and solemnly to consign into tits hands once and for all, in a symbolical and glorious representation, their delegated and expiring power. And then follows the divine Voice, as at the Baptism, commanding, however, here, in addition, the sole hearing and obedience of Him whose power and glory were thus testified.”

How, it is asked, did the disciples recognize these celebrated personages? And some have answered that our Lord may have subsequently informed them. But it appears by Matthew 17:4 that Peter knew them at the time. The disciples may have learned their identity by the conversation; or, more probably still, the same elevation of spirit by which they were able to see them at all enabled them to know, as by intuition, who they were. Probably the risen saints, after the crucifixion, were known in the same way.