Last month, I asked investment writer/analyst Eddy Elfenbein how his thinking had changed since the start of the financial crisis.

Elfenbein, who writes about investing at Crossing Wall Street, was named by CNNMoney as "the best buy-and-hold blogger" on the Web. To hear how a long-term-oriented investor has adapted his thinking over time, I expanded the question in the below video exchange. (Run time: 1:39; there's also a transcript below.)

Brian Richards: How has your investment thinking changed over the course of your career -- following stocks, writing about stocks, recommending them?

Eddy Elfenbein: A few things I've learned. One is it's just a truism: The trend can always go further than you expect, further than you thought. "The stock it's down to $9. It can't get any lower." And then it's at $6. And conversely, "it's at $8, it can't go any higher," and then it doubles. And so that's something I've always learned, that that end point is never where you think it's going to be.

And then I think the lesson of humility; I've learned more and more of what I don't know and I've learned to concentrate on the shrinking spheres that I do know, that I feel comfortable. I think when I started out investing I wanted to know everything. I wanted to know how all these companies work, and you know people will ask me about Groupon or this company. I just haven't the faintest idea what they do or how to value them, and I'm fine with that. [laughs] But I used to want be... I had to know this. I'm fine looking into companies that I know about.

For more from my interview with Eddy Elfenbein, see his take on how to go about selling stocks, or check out his site, Crossing Wall Street.