Apart from his accomplishments, Jon was a truly special person with respect to his habits of mind, his enthusiasm for life, his sense of humor, his overall graciousness and his perspectives on mathematics and on life. It was a privilege for me to have known him over the years. After his sudden death, I suddenly conceived of and wrote a paper that I have dedicated to him. None of this existed in my mind before his passing, and I deeply believe in the (Christian) idea of annunciation as a spur to creative action. [Gerald Beer, California State University, Los Angeles, CA, USA]