But there is something we can and must do: We must learn all the lessons we can.
Here are some:
1. The gulf between the decent and the indecent
Tamerlan Tsarnaev, the older brother, once told an interviewer before a Golden Gloves boxing competition: "I don't have a single American friend. I don't understand them."
The reason Tsarnaev didn't understand Americans was not primarily cultural. Tsarnaev came to America when he was 14 or 15, an...