Don Saari is a Distinguished Professor of Mathematics and of Economics, and he is the Director of the Institute for Mathematical Behavioral Sciences at the University of Califor- nia, Irvine. His research interests range from mathematical astronomy (e.g., the behavior of collisions and the evolution of the Newtonian N -body problem) to the mathematics of voting and decision rules, with an emerging interest in how mathematics can help resolve some of the fascinating mysteries coming from the behavioral sciences. Prior to moving to California in 2000, he was the Pancoe Professor of Mathematics at Northwestern Uni- versity. He is an elected member of the US National Academy of Sciences, the American Academy of Arts and Sciences, and the Finnish Academy of Science and Letters.