Professor Hubert Dreyfus of the University of California at Berkeley, Wood's current teacher, is one of the most popular picks among iTunes U students.

"I'm podcasting my course on Heidegger, 'On Time and Being,' which is the hardest philosophy book of the 20th century, I think, and the most important," Dreyfus said. "That surprises me that Heidegger has such an audience."

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