Mark Kac pioneered the mathematical theory of stochastic processes. His formulation of Brownian motion became famous as the "Feynman-Kac Formula". Mark was renowned for simple questions with profound answers -- such as, "Can one hear the shape of a drum?" -- whose answers require deep mathematics and have significant physical applications. Mark generously gave his time, advice, and energy to CNLS even though privately he complained that nonlinear studies is not a proper definition of a scientific endeavor, any more than non-elephant zoology is. The Kac Memorial Lectures provide us a yearly opportunity to celebrate his encouragement, wisdom and charm.
