I first met David after an economics class at Stanford where I'd just given a totally stupid answer-- he came up to me and offered to sit with me and take me through some of the material to help me catch up. It was very sweet and very caring. After that I came to also know his goofball grin and great attitude-- when David was around you just felt like the volume had been turned up in the world and fun was about to be had. What a great guy-- and what a great loss.