釋氏要覽 1.86

1.86

This is named after the color of the robes. The Sengshilüe states: "Question: What does the color of the black robes (zīyī) look like? Answer: Purple, yet light black. The Kaogongji states: 'Dipping three times makes it light red (xūn); dipping five times makes it dark red (zōu); dipping seven times makes it zī (blackish).' Thus we know that zī originally derives from crimson bird-head color, which is a reddish purple. Therefore, when the nun Jingxiu of the Liang saw the robes of the noble assembly, they were like ripe mulberries. This is a light reddish deep black."