By revelation, dear annalex. If you have the Holy Spirit, he teaches you all things and reveals all things. If you have the gift of discernment, you can also tell what's phony and what isn't. Being filled with the HS is the secret (if there is one). Love, Mxxx
See my recent post to Forest Keeper. Private revelations can come from many sources. St. Paul warns about them: "Are all prophets?".