Whoever realizes that the six senses aren't real, that the five aggregates are fictions, that no such things can be located anywhere in the body, understands the language of Buddhas.
But when you first embark on the Path, your awareness won't be focused. You're likely to see all sorts of strange, dreamlike scenes. But you shouldn't doubt that all such scenes come from your own mind and nowhere else.
. . . the fools of this world prefer to look for sages far away. They don't believe that the wisdom of their own mind is the sage . . . the sutras say, "Mind is the teaching." But people of no understanding don't believe in their own mind or that by understanding this teaching they can become a sage. They prefer to look for distant knowledge and long for things in space, buddha-images, light, incense, and colors. They fall prey to falsehood and lose their minds to insanity.
This one life has no form and is empty by nature. If you become attached by any form, you should reject it. If you see an ego, a soul, a birth, or a death, reject them all.