I just wanted to second (or rather "third") the tributes to Bernard Siegan. Unfortunately, I never met Prof. Siegan, but I well remember the exciting experience of reading his book Economic Liberties and the Constitution as a college sophomore. It certainly opened my eyes to many aspects of constitutional history that I had never even heard of before (and, as I later learned, neither had mainstream legal scholars at the time the book was written and for some time thereafter).
Sadly, Prof. Siegan never got the full credit he deserved for his pioneering efforts. And he also suffered the indignity of being "Borked" by the Senate.
But if you read almost any recent article or book on constitutional economic liberties, Siegan's influence shines through, even if the authors themselves often fail to recognize it.