Mauricio Fernandez posted this to ruby-talk: AFAIK he introduced the concept of "brain power consumption" (now renamed as "stress" in his last talk) for the first time.

That was the first time (I’m aware of) somebody stated that the main goal of a programming language isn’t expressive power (possibly by being close to natural languages, as Perl) nor ease of learning or usage, but making the programmer happier (which is a weighted mix of all other criteria).

www.rubyist.net/~matz/slides/oscon2003/index.html

Video of the ll2 talk: ll2.ai.mit.edu/