Analysis:

This quatrain by Saadi Shirazi explores the theme of unrequited love and the emotional turmoil it can cause. Let's break down the lines:

Line 1: دانی که چرا بر دهنم راز آمد

"Do you know why my secret has come to my lips,"
The speaker is asking a rhetorical question, implying that the reason for their revelation is obvious.

Line 2: مرغ دلم از درون به پرواز آمد؟

"And my heart’s bird has taken flight from within?"
This line uses a beautiful metaphor to describe the speaker's emotional state. The "bird of the heart" taking flight symbolizes the escaping of their emotions and secrets.

Line 3: از من نه عجب که هاون رویین‌تن

"Don’t be surprised if an iron mortar,"
This line introduces a striking metaphor: an iron mortar, a sturdy and inanimate object, is given human qualities.

Line 4: از یار جفا دید و به آواز آمد

"Having suffered injustice from a lover, begins to cry out."
The iron mortar, despite its hardness, can't withstand the pain of injustice, just as the speaker can't bear the pain of unrequited love.

Deeper Meaning:

This quatrain suggests that:

Love can break even the strongest: The iron mortar, a symbol of strength and durability, is broken by love.
The heart can't hide pain forever: The speaker's secret, held within their heart, eventually bursts out.
Unrequited love is painful: The speaker's suffering is so intense that even an inanimate object can empathize.

This quatrain is a powerful expression of the pain of unrequited love. By using the metaphor of the iron mortar, Saadi emphasizes the universality of suffering caused by love, even when it is directed towards something as seemingly unfeeling as an object.