Summarize this text:
The Way of husband and wife is intimately connected with Yin and Yang [these
are the two basis elements of the Universe: Yin, the soft yielding feminine element, and
Yang the hard aggressive male element. Every substance contains both elements in
varying proportions] and relates the individual to gods and ancestors. Truly it is the great
principle of Heaven and Earth, and the great basis of human relationships. Therefore the
"Rites" [The Classic of Rites] honor union of man and woman; and in the "Book of
Poetry" [The Classic of Odes] the "First Ode" manifests the principle of marriage. For
these reasons the relationships cannot but be an important one.