This is not only where ClearCase comes from, this is where "The Booch Method", UML, and the software for the Space Shuttle, The International Space Station, EuroControl (= pan-european air traffic control) and the F-22 fighter jet comes from. (Plus who knows how much other militarg hardware...)

It is a truly astonishing software development environment which with a a single key-press can answer questions like "what other code is affected if I change the default value of a parameter to this function". (Think about that one for a second!)