My grad math advisor was one of the folks who wrote significant parts in Urbana of the symbolic core; the behind the scenes team got legal settlements after that strange move. He's not from Silicon Valley; I think he'd done some early prototyping and coding himself while at CalTech (in Lisp if i recall) then came to Urbana-Champaign as a research prof, and got the team of several to build it out. [ I've been using it since 1988, and love it. ]