Happy Fourth of July. I'm thinking today of something the late Jacques Barzun wrote about "revolution" as a historians' category of event, and I think I will share it with you. Barzun defined "revolution" in a somewhat narrow way. Nowadays, if someone invents a new vacuum cleaner that can get the dust in the corners more easily than the older cleaners, he is likely to call it a revolutionary product. Even aside from marketing, you can find in dictionaries broad definitions of revolutions such as this: "far-reaching and drastic change." Thus, the late Helen Gurley Brown is both credited with and blamed for contributions to a "sexual revolution," the Vatican II council is said to have worked a "revolution" in Catholic doctrine, and the development of steam engines in the 18th century is widely said to have set off the "industrial revolution." Although each of those events fits in its own way into the broad story Barzun ...