So the student asked me — she said, “You didn’t explain to us the mechanism of action of nitroglycerine. I understand nitroglycerine is also an explosive.” And she said, “Well, certainly it couldn’t work by causing explosions.” I remember the class laughing. And I said, “No, of course not.” I said, “But you know, I’m not certain about the mechanism of action. It may not be known. That’s why I haven’t told you why. Let me look it up.” So, I spent the rest of the afternoon reading up on nitroglycerine. The mechanism was completely unknown. Being a chemist, I looked at the chemistry of nitroglycerine. It’s nitro. So it has actually three nitro groups — NO2 groups they’re called — on this little molecule, and I’m thinking, “Hmm, I just wonder whether one or more of those NO2 groups in the body maybe is converted to NO, which is nitric oxide.” So a couple of days later, we began to do those experiments in a laboratory. And after about two months of work, sure enough we found that our arteries metabolize or convert nitroglycerine to nitric oxide. So then we purchased some authentic nitric oxide gas, and we tested that pharmacologically, and we found that it produces all the identical effects of nitroglycerine. So we concluded that nitric oxide is the active species in the drug nitroglycerine. We published that, and then many people repeated that work and now we know how nitroglycerine works.