...the butterfly of life and death...There are two ways of looking at Yuuko's symbol - butterfly.
The butterfly has a special meaning in all cultures around the world... often related in some way to the idea of a person's soul, or of a transformation taking place in life. In fact, the ancient Greek word for butterfly is a word which actually means "soul" or "mind."1. Western myth:
In the greek mythology there is a myth in which two souls destroyed something beautiful to live forever... we still don't know why Yuuko's time was stopped, but we know that Shaoran stopped it to save Sakura's life, so it could be one reference to it. I still need to do some research on this one.
2. Eastern myth:
In eastern philosophy we have actually another explanation, that I think is more Yuuko's, in Japanese culture a butterfly is the personification of a person's soul, whether they be living, dying, or already dead.
3. Other myths:
In ancient Celtic culture, the butterfly symbolized rebirth and transformation. The Celtics also believed that butterflies had souls, and when they accidently became eaten by a female, they would impregnate the female and be born as a human.
In Christianity, a butterfly is deemed to be a symbol that represents the human life cycle, and often used in referring to the life, death, and resurrection of Christ.
In Mexico, butterflies are believed to be the souls of departed loved ones returning to visit. Butterflies are often associated with that nation's most famous of national festivals, Los Dias de Muertos (The Days of the Dead), because as many as 250 million butterflies arrive in Mexico from the north on or about the days of the festival, which takes place every year on November 1 and 2.
- Information taken from Hospice of the Gorge