Analysis:

This quatrain by Saadi Shirazi expresses deep and consuming love, to the point of obsession. Let's break down each line:

Line 1: شب‌ها گذرد که دیده نتوانم بست

"Nights pass, but I cannot close my eyes."
The speaker is unable to sleep because their thoughts are constantly occupied by the beloved.

Line 2: مردم همه از خواب و من از فکر تو مست

"All people are asleep, but I am intoxicated by thoughts of you."
While the world is at rest, the speaker is consumed by an intoxicating love for the beloved.

Line 3: باشد که به دست خویش خونم ریزی

"Perhaps you will pour out my blood with your own hand."
This line expresses a masochistic desire for the beloved's attention, even if it means suffering harm.

Line 4: تا جان بدهم دامن مقصود به دست

"So that I may give my life in your service."
The speaker is willing to sacrifice everything, even their life, for the sake of their love.

Themes explored in the quatrain:

Consuming love: The love expressed is so intense that it consumes the speaker's thoughts and prevents them from sleeping.
Masochism: The speaker seems to derive pleasure from the idea of suffering for their beloved.
Self-sacrifice: The speaker is willing to sacrifice their life for the sake of their love.

In essence, this quatrain is a powerful exploration of obsessive love, showcasing the lengths to which a person might go for someone they adore. It's a testament to the intensity of human emotions and the complexities of love.