Pauli's 2nd exclusion principle precludes Wolfgang Pauli from sharing a room with an experiment conducted successfully. Something would always go wrong, and—legend has it—Pauli's colleagues aimed to prove it one day with a chandelier.
They rigged that chandelier (which hung into a lab room) so one of them could let it fall just as Pauli entered the room. When Pauli did enter the room as predicted, the principle was upheld—as was the chandelier: a pulley got stuck.
So, there you have it: the principle inside, in a way, the principle. How about an email inside, in a way, an email?
›› Forward an email in full and the state in which you received it. Outlook lets you forward messages as EML attachments. These include all the formatting and text as well as the complete header information.