In the seen will be merely the seen; in the heard will be merely the heard; in the thought will be merely the thought; in the known will be merely the known.
Who comes, ultimately comes not. Who goes, ultimately goes not. Why? Coming is not really known in coming, and going is not really known in going. What is seen is not to be seen again, ultimately.
In that way, what is seen, heard, thought, or known, all of this is unreal, like a dream.