As a result of the phenomenally rapid change and growth of physics, the men and women who did their great work one or two generations ago may be our distant predecessors in terms of the state of the field, but they are our close neighbors in terms of time and tastes. This may be an unprecedented state of affairs among professionals; one can perhaps be forgiven if one characterizes it epigrammatically with a disastrously mixed metaphor; in the sciences, we are now uniquely privileged to sit side-by-side with the giants on whose shoulders we stand.

Bahn's Law of Rocketry: Amateurs talk Propulsion, Professionals Talk Insurance.