《偏微分方程讲义(英文版)》讲述了：In the mid-twentieth century the theory of partial differential equations wasconsidered the summit of mathematics, both because of the difficulty andsignificance of the problems it solved and because it came into existence laterthan most areas of mathematics.

Nowadays many are inclined to look disparagingly at this remarkable areaof mathematics as an old-fashioned art of juggling inequalities or as a testingground for applications of functional analysis. Courses in this subject haveeven disappeared from the obligatory program of many universities （for ex-ample, in Paris）. Moreover, such remarkable textbooks as the classical three-volume work of Goursat have been removed as superfluous from the library ofthe University of Paris-7 （and only through my own intervention was it possi-ble to save them, along with the lectures of Klein, Picard, Hermite, Darboux,Jordan ）