Robert Sprague's law

Which brings me back to another Robert Sprague quote — I didn't bring the overhead for it. Sprague's law: anything with anything tensile, in compression — the biggest use of any composite in the world is Portland cement, mortar and rock. That's a composite material, but you design it for compression, and you put steel rod in when it has to be in tension. So I'm not knocking composites completely. I'm just saying when people talk about high-performance composites, they're often not worrying about the cost. That's where you get Jim Williams' corollary: whenever you first hear about the cost of a new material, write it down, because that's the lowest cost you'll ever have.