If on my theme I rightly think,
There are five reasons why men drink,—
Good wine, a friend, because I'm dry,
Or lest I should be by and by,
Or any other reason why.
Source, in full
Causæ Bibendi, reported in Bartlett's Familiar Quotations, 10th ed. (1919). These lines are a poetic translation of a Latin epigram (erroneously ascribed to Henry Aldrich in the Biographia Britannica, second edition, vol. i. p. 131), which Menage and De la Monnoye attribute to Père Sirmond
Notes from Wikiquote
Si bene commemini, causæ sunt quinque bibendi:
Hospitis adventus; præsens sitis atque futura;
Et vini bonitas, et quælibet altera causa.
Menagiana, vol. i. p. 172.