Thanks everyone for the great suggestions! Tonight I'm teaching my students about the origins of graphical interfaces, and realized that I didn't have a good answer ready to the question of, "But what inspired Bush?"

I am quickly reading Smith, Googling about Otlet/Goldberg, and running to our university library to get Burke's book.

Does anyone have documentation, or good theories, about how/where Vannevar Bush was inspired to develop his ideas for the speculative Memex? I know that he was privy to the latest computer developments, but how did he make the jump from plugboards and punch cards to a virtual encyclopedia and hypertext?