Alan Kay has got to be one of the smartest people alive. I wish he wrote more. My favorites are his answer to the question "What do you believe is true, even though you cannot prove it?":
One idea that Kay has championed is what he called somewhere "recursive design", in which you begin with a kernel that is both simple and universal and then build the rest of a complex system in terms of that. The relation to Lisp is obvious, and Lisp and Smalltalk environments are probably the best examples of systems designed this way. I'm curious what other examples people here might cite.
http://www.edge.org/q2005/q05_8.html#kay
and his essay "Predicting the Future":
http://www.ecotopia.com/webpress/futures.htm
His other work is quite impressive, also, but these two are by far my favorites.