Here is what I got. I had thought only "teardrop" can be counted. Turns out "tear" can be counted also. So "a tear" and "a teardrop" both are fine.
It's said "a tear" is more down-to-earth saying. While "a teardrop" is more peotic/fancy presentation. Since this book is about dark-side of history, so maybe "a tear" is better choice.
Each tear/teardrop is precious. Hope the history doesn't always repeat.
