~ Jss was gar ist ~
This is a 1 L. salt-glazed stoneware stein made in the Westerwald ca. 1900. The verse is an old German proverb/rhyme and good advise. Note that the "Old German/English" use of "J" before a consonant has the same meaning and sound as "I" in "Modern German/English". The word "iss" is the imperative (command) form of "essen" (to eat).
Jss was gar ist.
Trink was klar ist.
Sprich was wahr ist.
Lieb was rar ist.
Eat what is cooked.
Drink what is clear.
Speak what is true.
Love what is rare.

Three of the lines from this verse can be found below on this pass cup, ca. 1900, made by
Johann Peter Thewalt, mold #1197.
Translation: Les Hopper compilation
Photo credits: unknown, Rich Stattler