Analysis:
This quatrain by Saadi Shirazi is a poignant plea for compassion, contrasting the harsh realities of war with the possibility of mercy.

The Warrior Child: The speaker addresses a young warrior, highlighting their prowess in battle but also their capacity for cruelty.
Breaking Hearts: The image of breaking hearts "like the heart of a non-believer" suggests a deep emotional wound. It implies that the warrior's actions are causing immense suffering.
The Call for Mercy: The speaker argues that it is better for the warrior to focus on their skills as a horseman rather than inflicting harm on others. This suggests a preference for peace and compassion over violence.

Themes:

The Cruelty of War: The quatrain highlights the destructive nature of war and the suffering it inflicts.
The Call for Compassion: Despite the warrior's prowess, the speaker calls for compassion and mercy.
The Choice Between Violence and Peace: The quatrain presents a stark choice between the path of violence and the path of peace.

Deeper Meaning:

This quatrain is a timeless reminder of the human cost of war. It suggests that even in the midst of conflict, there is always the possibility for compassion and understanding. The speaker's plea for mercy is a universal one, resonating with anyone who has experienced the pain of war or violence.

This quatrain is a powerful indictment of war and a call for humanity to choose peace over violence.