ELI5 - Originary Interest

I'm listening to "Human Action" as an audio book on my commutes, and missed exactly what "originary interest" is. (Paying attention to driving, passengers, and Human Action can require a bit more focus than I can deliver on a consistent basis.) Can someone give me a quick explanation of originary interest? Feel free to dumb it down if that helps. I'll be listening to the chapter again, but I'd like to go back with a better understanding as it seems fairly important.

link: http://ift.tt/1oNXuhn