Analysis:

This quatrain by Saadi Shirazi is a beautiful and evocative expression of romantic longing. It's filled with imagery and symbolism that speaks to the depth of the poet's love.

Imagery of the cup: The "half-empty cup" is likely a metaphor for the beloved's heart. The poet is suggesting that they would be content with even a small part of the beloved's affection.
The mole: The mole is a common motif in Persian poetry, often used to represent a beauty mark. Here, it symbolizes the beloved's unique and captivating qualities.
The idea of sacrifice: The poet is willing to sacrifice their life (represented by the "head") in pursuit of their love. This highlights the intensity of their feelings.

Deeper Meaning

This quatrain explores themes of love, longing, and sacrifice. The poet is expressing a deep desire for union with their beloved and is willing to go to great lengths to achieve this. The imagery of the cup and the mole suggests a longing for a deeper connection and a desire to possess every aspect of the beloved.

Key Themes:

Romantic longing: The poet's intense desire for their beloved is evident throughout the quatrain.
Sacrifice: The poet is willing to sacrifice their life for their love.
Symbolism: The cup and the mole are used as powerful symbols to represent the beloved and the poet's desire.

Overall

This quatrain is a testament to the power of love and the lengths to which people will go for those they love. The poet's vivid imagery and heartfelt expression create a lasting impression.