Source, in full
Attributed to Parker after her death, by Robert E. Drennan The Algonquin Wits (1968), p. 124. However the same quip appears anonymously fifteen years earlier, in the trade journal Sales Management (Chicago: Dartnell Corp., 1918-75), vol. 70 (Survey of Buying Power, 1953), p. 80: "Marxism never changes. You can’t teach an old dogma new tricks."