It astonishes me that Brookline Booksmith continues to survive simply because it is THAT GOOD. I mean, not that it isn't THAT GOOD, but the demise of many other lovely local bookstores over the past decade (I still cry for Wordsworth in Harvard Square) suggests strongly that, in the world of small bookstores, being THAT GOOD is not nearly enough. I have no idea what their secret is. It may have something to do with the character of the citizens of Brookline; if so, I wish someone would isolate this factor so we could put it in everybody else's drinking water.