On this day in 1610 Galileo saw the four largest moons of Jupiter for the first time. He was 45. It was the first time anyone had seen the moons of Jupiter, and it's hard to think how anyone Galileo spoke to made sense of what he was describing. The moon, our moon, was a large bright disk in the sky; Jupiter was a pin prick by comparison. Brighter, certainly, than the other stars, but it was hard to imagine moons revolving around something so insignificant.
Galileo was a revolutionary. His telescope made the universe more enormous than anyone knew, larger than we could imagine, in a word: infinite. You might think this would make God infinitely larger as well, something the church would applaud and advertise. But it was mischievous to change the way people thought of the heavens. Faith doesn't know how to handle adjustments. Faith is supposed to be uniform and unchanging. The Vatican was his employer, and they thanked Galileo by freezing his salary. Eventually they stood him up in front of the Inquisition and had him recant what he knew. Galileo appears six times in A Book of Ages.
When you think about it, most of the great revolutionaries haven't been wild-eyed youths but middle aged men and women. People who've lived long enough to recognize that change is a natural part of how the world operates. People like Rosa Parks and Charles Darwin, Ben Franklin and Galileo precipitated revolutions that endured beyond their own time.