"dreams come from the stomach"

   A line from Act V, Scene 1 of German playwright Friedrich Schiller’s popular drama The Robbers (1781).  The hollow assertion that dreams "come from the stomach and cannot signify anything" is uttered by Franz, the play's archetype of morally bankrupt rationalism, in a vain attempt to dismiss the guilty visions which torment him. 

Online script of the play at Project Gutenberg