Analysis of the Quatrain:

This quatrain by Saadi Shirazi delves into the complexities of love and the challenges of unrequited or difficult love. Let's break down the lines:

Line 1: چون دل ز هوای دوست نتوان پرداخت

"Since one cannot free the heart from the desire of a friend,"
The poet begins by acknowledging the powerful and inescapable nature of love. The heart, he suggests, is often unable to free itself from the longing for a beloved.

Line 2: درمانش تحمل است و سر پیش انداخت

"The remedy is endurance and bowing the head."
This line offers a practical solution to the heart's longing: patience and humility. The lover is advised to endure the pain of unrequited love and to accept their situation.

Line 3: یا ترک گل لعل همی باید گفت

"Either one must say farewell to the ruby lip,"
The poet presents a difficult choice: to give up on the beloved entirely. The "ruby lip" is a metaphor for the beloved's beauty and allure.

Line 4: یا با الم خار همی باید ساخت

"Or endure the pain of thorns with the rose."
The final line offers another option: to accept the pain that comes with love. The image of a rose with thorns suggests that beauty and pain are often intertwined in love.

Themes explored in the quatrain:

The inevitability of love: The poet suggests that love can be a powerful and consuming force that is difficult to resist.
The pain of unrequited love: The quatrain explores the suffering that can come with unrequited or difficult love.
The choice between love and pain: The poet presents a difficult choice: to give up on love or to endure the pain that comes with it.
The beauty and pain of life: The image of a rose with thorns suggests that life is full of both joy and sorrow.

In essence, this quatrain is a reflection on the complexities of human relationships and the challenges of love. It offers a wise and empathetic perspective on the pain of longing and the choices that lovers often face.