Mark Vishik was one of the prominent figures in the theory of partial differential equations. His ground-breaking contributions were instrumental in integrating the methods of functional analysis into this theory. In this book, friends and pupils of Mark Vishik remember his life and work. From his early years as a student to his connection with the Lwow school of Stephan Banach and to his later career as a respected teacher and mentor, Vishik's legacy is explored in detail. His research and pedagogical work influenced hundreds of undergraduate and graduate students, many of whom went on to become leading figures in their own right. The reader is introduced to a number of remarkable scientists whose lives intersected with Vishik's, including S. Banach, J. Schauder, I. N. Vekua, N. I. Muskhelishvili, L. A. Lyusternik, I. G. Petrovskii, S. L. Sobolev, I. M. Gelfand, M. G. Krein, A. N. Kolmogorov, N. I. Akhiezer, J. Leray, J.-L. Lions, L. Schwartz, L. Nirenberg, and others.