Analysis:

This quatrain by Saadi Shirazi is a passionate and evocative expression of love, longing, and the fear of loss.

Metaphor of the Wine Cup: The wine cup is a common metaphor for beauty and love in Persian poetry. Here, the empty cup symbolizes the speaker's longing for the beloved's lips.
Fear of Separation: The fear of "empty vessels" without the beloved's presence suggests a deep-seated fear of death or existential emptiness.
The Intensity of Love: The imagery of filling countless cups and the fear of losing one's life emphasize the intensity and all-consuming nature of the love.

Themes:

Love and Longing: The central theme is the intense longing for the beloved and the fear of separation.
Mortality and the Fear of Death: The quatrain hints at the fragility of life and the fear of death, especially when separated from the beloved.
The Metaphysical Nature of Love: The love described is not merely physical but also spiritual, connecting the lovers on a deep metaphysical level.

Deeper Meaning:

This quatrain beautifully captures the human condition, exploring themes of love, loss, and the fear of death. The imagery of the empty cup and the fear of becoming an "empty vessel" suggests a deep-seated fear of existential emptiness without the beloved. It's a testament to the power of love to both sustain and consume us.

This quatrain is a poignant expression of the human heart, exploring the complexities of love, loss, and the fear of mortality.