I wanted to properly cite the following awesome quote:

Every mathematician has a secret weapon. Mine is Morse theory. - Raoul Bott

Now this has been attributed to Bott in precisely two places that I can find: the older of the two is Bestvina's work on PL Morse theory here and the more recent occurrence is in the 14th slide of Kahle's talk available as a rather large pdf file here.

Question:

What is the original reference for this quote?

I've combed through the likely suspect, Morse theory indomitable available here but the quote does not appear to be in that paper