I recently read a quote attributed to Spencer Tracy. I cannot locate my source; I cannot verify it; nor can I remember it exactly. It was approximately as follows:

Whenever actors (an actor) wants to get into politics, he should remember John Wilkes Booth.

Please help me out with the accurate quote and its provenance.

Don't know if he did or didn't, but somebody sure needed to say it.

Here is the correct quotation:

Actors who get into politics should remember what happened to John Wilkes Booth.