Daniel Miessler has interesting post, which refers to a sequence of videos posted on YouTube. Each video is just under 10 minutes long. If you're pressed for time just watch the third one, but watching the whole series is definitely worth while. The series covers a lecture delivered at the end of the previous century by emeritus prof. Albert Bartlett of the University of Colorado at Boulder.

Episode 1

Episode 2

Episode 3

Episode 4

Episode 5

Episode 6

Episode 7

Episode 8