The title nods to Omar Khayyam, whose famous verses imagine happiness as a jug of wine, a book of verse and quiet company. Bonta keeps the wine and the book but shrinks the scene to almost nothing: two small things and one person.
The surprise comes in the second stanza. Normally we feel satisfied when we finish something. Here the speaker is delighted that he couldn't. Both the bottle and the book turn out to be "little worlds," and they held more than he could use up. Their depth is the joy.
The last lines turn into a quiet prayer. He asks heaven to fill him, and to be his cellar, a place where wine is stored and never runs out. The mood is warm, humble and a little playful. He wants abundance rather than an ending, and he seems content to be a person who will never quite reach the bottom of things.