Original source here, from Saturday Morning Breakfast Cereal and “Never Forget” version here.

Thanks to Unlearning Economics for flagging this funny and moving poster. When I asked him the source, he tweeted: 

@mileskimball it’s actually a joke comment but I prefer the never forget version, bleeding heart that I am: http://www.smbc-comics.com/index.php?db=comics&id=1535#comic…

By that measure, I may be not just a supply-side liberal, but a bleeding-heart supply-side liberal.