I was curious, how do materials find their way into medicine?  And I was a chemical engineer, I thought — I was a young guy — I thought it must be chemists or chemical engineers.  But as I looked into this, I found that was almost never true.  When I looked at this, I found — pretty much in the 20th century, when I was doing work — that almost every material that ever came into medicine was actually driven by a medical doctor.  And what they pretty much always did is, whenever they wanted to solve a medical problem, they went to their house and they found some object in their house that kind of resembled the organ or tissue — from a material standpoint — that they wanted to fix.  So for example, in 1967 some of the clinicians at the NIH wanted to make an artificial heart, and they said, “Well, what object has a good flex life, like a heart?” and they said, “A ladies girdle.”  So they took the material in that, and made the artificial heart out of it.  That, of course, has led to some problems.  When blood hits the surface, the artificial heart forms a clot. The clot can go to the patient’s brain, they can get a stroke and they can die.  Another example is one of the materials used in a woman’s breast implant is actually a mattress stuffing, because it’s squishy and it’s a polyurethane. I was a chemical engineer. I didn’t think that way.  I thought, one of the things you learn in chemical engineering is design.  So what I started saying is, rather than take it from your house, why don’t you ask the question, “What do you really want in this material from an engineering standpoint, chemistry standpoint, biology standpoint?”  You could put those on the board, write this out and say, “Well, these are the properties I want. I’m going to then synthesize it and make it from scratch.”