himym x chemistry

Ted: "It's just, everyday I think I believe a little less, and a little less, and a little less. And that, sucks. What do I do about that, Scherbatsky?"
Robin: "You're Ted Moseby. You start believing again."
Ted: "In what, destiny?"
Robin: "Chemistry. If you have chemistry you only need one thing..."
Ted: "What's that?"
Robin: "...Timing. But timing's a bitch."

Tell me something I don't know.