22. As a rule of thumb, historians say, the results of technological innovation always take longer to reach fruition than early champions of change predict.
You know, italian housewives have a rule of thumb. A handful of dry pasta about an inch in diameter is Sufficient for each person as it doubles in volume when cooked.
On the other hand, it is a rule of thumb in biology that females (of any species) are much pickier than males. There are good evolutionary reasons why that is so.