Analysis:

This quatrain by Saadi Shirazi is a beautiful, yet cautionary, exploration of love, desire, and the consequences of our actions.

The Nightingale as a Metaphor: The nightingale, known for its beautiful song and its deep connection to love, is used as a metaphor for a person deeply in love.
The Dangers of Obsession: The nightingale is described as being "intoxicated by desire" and "bound by passion." This suggests a state of obsession that could lead to self-destruction.
The Consequences of Self-Inflicted Wounds: The final couplet warns that the nightingale's self-imposed captivity might prevent it from reaching its beloved friends. This implies that our own actions and words can sometimes be our biggest obstacles.

Themes:

Love and Desire: The central theme is the power of love and desire, which can both elevate and ensnare.
Self-Inflicted Suffering: The quatrain suggests that we often create our own suffering through our actions and choices.
The Importance of Connection: The longing for connection with loved ones is a recurring theme, and the nightingale's inability to reach its friends is a poignant symbol of this desire.

Deeper Meaning:

This quatrain can be interpreted as a cautionary tale about the dangers of unchecked passion. It reminds us that while love can bring great joy, it can also lead to suffering if it consumes us entirely. The nightingale's plight serves as a metaphor for the human condition, highlighting our capacity for both great beauty and great self-destruction.

This quatrain is a timeless exploration of the human heart, reminding us to balance our passions with wisdom and to avoid letting our desires consume us.