Willis Rodney Whitney ... once compared scientific research to a bridge being constructed by a builder who was fascinated by the construction problems involved. Basic research, he suggested, is such a bridge built wherever it strikes the builder's fancy-wherever the construction problems seem to him to be most challenging. Applied research, on the other hand, is a bridge built where people are waiting to get across the river. The challenge to the builder's ingenuity and skill, Whitney pointed out, can be as great in one case as the other.