“All Cognac is brandy, but not all brandy is Cognac”

Entry in progress—B.P.
 
Google Books
Wine without Frills:
Everyday Enjoyment of Imported Wines and Spirits
By the Schenley Import Corporation
New York, NY: Schenley Import Corporation
1939
Pg. 58:
Ques. Are “Cognac” and “Brandy” synonymous terms?
Ans. No. All Cognac is brandy, but not all brandy is Cognac.
 
Google Books
Deviance &Respectability:
The Social Construction of Moral Meanings
Edited by Jack D. Douglas
New York, NY: Basic Books
1970
Pg. 336:
The relationship between deviance and respectability is much like that of cognac and brandy: as all cognac is brandy, but not all brandy is cognac; so, too, all deviance is other than respectable, but not all that is other than respectable is deviant.
 
Google Books
Alcohol, Proof of What?
By Essie E. Lee
New York, NY: J. Messner
1976
Pg. 52:
All cognac is brandy, but not all brandy is cognac.
 
Napa Valley (CA) Register
May 21, 2015
The Wine Exchange by Allen R. Balik
Cognac. a wine or spirit?
(...)
In any discussion of brandy and Cognac, it is important to remember the old adage, “While all Cognac is brandy, not all brandy is Cognac.”