And this voice which came from heaven we heard, when we were with him in the holy mount. In our human thinking we are constantly looking for things to occur miraculously. Peter laid forth a very startling truth, that prophecies are more sure than miracles. That is an astounding statement. Prophecies can be historically verified, but often miracles cannot.
Prophecies are verifiable in their fulfillment.
Also, prophecies, in their understanding and fulfillment, can be seen and enjoyed by all, whereas often miraculous occurrences cannot. That was a glorious, miraculous event, but only three people enjoyed it. God declares the things not yet done as if they had already occurred because He knows the end from the beginning. He, through prophetic avenues, can declare the end before it begins. He spoke from ancient days of things that had not yet occurred as though they had occurred.