Analysis:

This quatrain by Saadi Shirazi delves into the complexities of human nature, particularly the tension between spiritual aspiration and earthly desires. Let's break down the deeper meanings:

Servant of Nature: The first line suggests that the poet feels trapped by their human nature, subject to its limitations and desires.
Distance from the Divine: The second line indicates a sense of spiritual separation or alienation. The poet feels distant from a higher power or divine source.
The Power of Love: Despite these spiritual and existential struggles, the poet is deeply in love. This love, paradoxically, gives them life and purpose.
Paradox of Love: The last line presents a paradox: the love that causes the poet pain also gives them life. It is a love that both kills and sustains them.

Themes:

Spiritual longing: The poet expresses a desire for a deeper spiritual connection.
The human condition: The quatrain explores the complexities of human nature, including our limitations, desires, and capacity for love.
Paradox of love: Love is portrayed as a powerful force that can both give life and cause pain.

Deeper Meaning:
Saadi's quatrain suggests a deep understanding of the human condition. The poet is grappling with questions about the meaning of life, the nature of God, and the power of love. The paradox of loving something that causes pain is a universal human experience.

This quatrain is a meditation on the human soul. It explores the tension between our earthly desires and our spiritual aspirations. The poet's ability to find beauty and meaning even in the midst of pain is a testament to the enduring power of the human spirit.