A Thousand Splendid Suns

Why did Hosseni name his book A Thousand Splendid Suns? It is not enough to tell me that it is part of a line from a poem. Is the dedication in the book any clue, perhaps?
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Why did Hosseni name his book A Thousand Splendid Suns? It is not enough to tell me that it is part of a line from a poem. Is the dedication in the book any clue, perhaps?