There is a Talmudic legend about a pagan approaching Hillel the Elder, offering to convert to Judaism if Hillel could explain the Torah to him while standing on one foot. (In “an elevator speech” might be a modern idiom.)
Hillel answered: “That which is hateful unto you, do not do unto any other. That is the whole Torah: all the rest is commentary/corollary. Now go forth and study that.“
Similarly, if anybody were to ask Steven Levitt/Shlomo HaLevy to explain all of economics while standing on one foot, his answer might well be something like:
People respond to incentives. This is the essence of economics: all the rest follows from that. Now go forth and study it.