从《周易》诞生的时代起,奇数为阳,偶数为阴,已是通则,在性别上的对应,自然应当是奇数为男,偶数为女.不过,存在一个出格的例外,即奇数、阳数“七”往往和女性联系在一起,和女子的生长、衰老密切相关.在民间习俗和古老的传说、故事中,“七”往往还是伴随妇女爱情、婚姻等终身大事和一生休戚的命运之数. From the era of the birth of the “Book of Changes”, the odd number is the positive and the even number is the negative, which is already the general rule. In the gender correspondence, it is natural that the odd number should be male and the even number should be female. However, there is a special exception, Number “seven” is often associated with women, and women's growth, aging is closely related to the folk customs and ancient legends in the story, “seven” is often accompanied by women's love, marriage and other lifelong events and life fate number.