“Nothing comes out of the pot but the steam that is in it.”
Gaelic folk saying. I am familiar with it as I am Scottish
Some old folks have expanded on that as folks have a tendancy to do.
Of course, if water boils in a pot, steam comes out of the pot and also pictured steam comes out of the pictured pot. But what if one insisted on saying that there must also be something boiling in the picture of the pot?
Wittgenstien, Philisophical Investigation