John 18:19 Meaning

17Then saith the damsel that kept the door unto Peter, Art not thou also one of this man's disciples? He saith, I am not.

18And the servants and officers stood there, who had made a fire of coals; for it was cold: and they warmed themselves: and Peter stood with them, and warmed himself.

19The high priest then asked Jesus of his disciples, and of his doctrine.

20Jesus answered him, I spake openly to the world; I ever taught in the synagogue, and in the temple, whither the Jews always resort; and in secret have I said nothing.

21Why askest thou me? ask them which heard me, what I have said unto them: behold, they know what I said.