He was influenced by Thomas Malthus' work, "An Essay on the Principle of Population" written in seventeen ninety-eight.

VOA: special.2009.02.25

Instead,it will be based on a simple principle: whether a state is ready to do what works.

VOA: special.2009.07.30

"So instead of maybe doing a lecture on a scientific principle, we may learn a science song about it, or a rap or perform a dance that sort of uses our body to explain a scientific phenomenon.

VOA: standard.2009.11.25