How Did Peter Know the Content of Paul’s Letters? Each letter was hand written, so copies could only be made by hand.

2 Peter 3:14. For which reason, beloved, since you expect these things you must now make every effort to be found spotless and blameless in Him in peace 15. and you must always consider the patience of our Lord for salvation, just as also our beloved brother Paul wrote to you, according to the wisdom given to him, 16. as also in all his letters when he speaks in them about these things, in which some things are hard to understand, in which the unlearned and unstable people are twisting them as they also do the rest of the Scriptures to their own destruction.