Justin Martyr, Dialogue with Trypho 7

What need, then, is there for a teacher from whom anyone could benefit, if the truth is not found in these matters? Long before any of the so‑called philosophers there lived certain men—older, blessed, righteous, and beloved by God—who spoke by the divine Spirit and foretold events that are now occurring; they are called prophets. These alone both saw and declared the truth to humanity, neither intimidated nor swayed by anyone, nor overcome by a desire for glory. Filled with the Holy Spirit, they spoke only what they had heard and seen. Their writings survive to this day, and anyone who reads them can gain great benefit concerning first principles, the end, and all that a philosopher ought to know, provided he believes them. They did not support their words with proof at the time, because they were trustworthy witnesses to the truth, standing above every proof. The events that have happened and continue to happen compel agreement with what was spoken through them. Moreover, they were also worthy of belief because of the powers they performed, since they glorified the Creator of all things, God the Father, and proclaimed the Christ, His Son. False prophets, filled with a deceitful and unclean spirit, have never done this and never do; instead they dare to work certain wonders to astonish people and they glorify the spirits of deceit and demons. I pray that, above all, the gates of light may be opened to you, for these things are not understood or perceived by everyone unless God grants understanding together with His Christ.