The Sequence of the Hexagrams states: 'Only after there are Heaven and Earth are there the ten thousand things; only after there are the ten thousand things are there male and female; only after there are male and female are there husband and wife; only after there are husband and wife are there father and son; only after there are father and son are there ruler and minister; only after there are ruler and minister are there superior and inferior; only after there are superior and inferior do ritual and righteousness have a place to be established.'
Heaven and Earth are the root of the ten thousand things; husband and wife are the origin of human relations. Therefore, the Upper Classic begins with The Creative (Heaven) and The Receptive (Earth), while the Lower Classic begins with Influence (Wooing), followed by Duration.
Heaven and Earth are two entities, so the two hexagrams are divided into the Dao of Heaven and Earth. Male and female unite to become husband and wife, so Influence and Duration both combine two trigrams to form the meaning of husband and wife.
Influence means stimulation, taking joyousness as primary; Duration means constancy, taking correctness as the foundation. In the way of joyousness there is naturally correctness; in the way of correctness there is naturally joy.
Being gentle and moving, with firm and yielding both responding, is joyous. In Influence as a hexagram, The Joyous (Lake) is above and Keeping Still (Mountain) is below, representing the youngest daughter and youngest son.
In mutual stimulation between male and female, none is deeper than when both are young; hence the two young ones form Influence. The body of Keeping Still is solid and sincere; stopping conveys the meaning of heartfelt sincerity.
The young man's will is sincere, humbling himself to interact below; the maiden's heart is joyous, responding above. The male is the first to stimulate: the male first stimulates with sincerity, then the female rejoices and responds.
Influence means stimulation; not calling it gan (stimulation) is because xian carries the meaning of 'all'—male and female mutually stimulate each other. In mutual stimulation of things, none compares to male and female, and young ones are even more intense.
In general, ruler and minister, superior and inferior, down to all things, all share the way of mutual stimulation. When things stimulate one another, there is the principle of success and breakthrough.
If ruler and minister can stimulate each other, the way of ruler and minister flows freely; if superiors and inferiors can stimulate each other, their intentions connect; down to father and son, husband and wife, relatives and friends, when sentiments and intentions resonate mutually, there is harmony, compliance, and success.
All affairs and things are like this; hence Influence contains the principle of success. 'Perseverance is beneficial': the way of mutual influence finds its benefit in correctness; if not correct, it falls into evil.
Like husband and wife uniting through wanton lust, ruler and minister pleasing through flattery, superiors and inferiors engaging in depravity—these are all cases where mutual stimulation is not correct.
'Taking a maiden brings good fortune' is spoken in terms of the hexagram's capacity. The hexagram has the yielding ascending and the firm descending, two qi stimulating and responding to each other, stopping and rejoicing, the male humbling himself before the female.
Taking a maiden with this meaning attains correctness and good fortune. The Tuan Commentary says: Influence means mutual stimulation.