"What is the sound of one hand clapping?" is the ancient Zen Buddhist riddle supposedly leading to enlightenment. And yet here on Medium, one clap seems kind of stingy, doesn't it? If, after viewing a live performance, I just brought my hands together once, I wouldn't be conveying appreciation--in fact the opposite. More of a sarcastic sneer.
Initially I didn't realize I could clap more than once, so maybe I unintentionally sneered at some writers' efforts. I am consciously more generous now. I know how much time, and how much heart, goes into my own work, so if it's this easy to encourage others, why wouldn't I put my hands together more often for writing I enjoy?
As you say, Christina, it's fun to give someone else a boost!