The Power and Philosophy of Ruby. Yukihiro Matsumoto gave a presentation at OSCON in which he discusses the influence of languages on thought, productivity and stress:
Principle of Human Interface
Languages can be viewed as interface. The important guidelines for good interface are:
Consistency
Flexibility
Succinctness
Stumbled across this one while reading the Slashdot comments on Larry Wall's latest State of the Onion screed. (Can't say that I ever get much out of the Onion addresses but some people seem to believe they are fecund).
VERY good presentation. Makes me want to run out and look at Ruby again. Matsumoto sounds like a very sharp man. I wish I could have heard the presentation live.