I’ve had this bookmarked for a long time (translation: I have no idea who I swiped this from, so thank you to whomever it was) but never had time to read it: The Story Behind the Lisa (and Macintosh) Interface. It lists the original Goals and Guiding Principles, which are now common UI design principles, a few of which are often just taken for granted. The email introduction to the paper notes that screen shots which pre-date the legendary visits to Xerox Parc by Steve Jobs show that the user interface was not entirely lifted from the Star design. Included also is The Pictorial History of the “Apple Desktop Interface”.