I don’t think there is anything I have done that I wish I hadn’t done. Because I learn from everything I do. I’m in school every day. My diploma will be my tombstone.
Eartha Kitt (1927-2008) American singer and actress
In Lon Tuck, “It’s Been a Long Time But … Eartha’s Back!” Washington Post (1978-01-19)
(Source)
When a citation is given to this quotation, it's usually "Playbill 1978." It does indeed show up in an (unknown month) of Playbill Magazine in 1978, also in association with her starring role in the stage show Timbuktu, which opened on Broadway March 1st of that year, but this article appears to be the source. (see comments for the helpful tip).
