時得而治矣，時得而化矣，時失而亂矣。
When yin and yang shrink and swell, the transformation of things falls into periods.
是故人生而不具者五：目無見，不能食，不能行，不能言，不能施化。
When the proper time is obtained, things come into order; when the proper time is obtained, these things are transformed.
故三月達眼，而後能見。
When the proper time is lost, disorder ensues.
七月生齒，而後能食。
Thus, it follows that in human life there are five insufficiencies: inability to see, inability to eat, inability to walk, inability to speak, and inability to transform.
期年生臏，而後能行。
Thus, it takes three months to control the movement of the eyes; only then can one see.
三年顖合，而後能言。
It takes seven months for teeth to be formed; only afterward can one eat.
十六精通，而後能施化。
It takes a full year for the kneecaps to be formed; only afterward can one walk.
陰窮反陽，陽窮反陰，故陰以陽變，陽以陰變。
故男八月而生齒，八歲而毀齒，二八十六而精小通。
It takes three years for the cranium to be formed; only then can one talk.
女七月而生齒，七歲而毀齒，二七十四而精化小通。
At age sixteen the passage for seed becomes complete; only then can one cause transformations to occur.
不肖者精化始至矣，而生氣感動，觸情縱欲，故反施亂化。
When yin is exhausted, it turns to yang; when yang is exhausted, it turns to yin; thus, yin relies on yang to change, and yang relies on yin to change.
故詩云：「乃如之人，懷婚姻也，大無信也，不知命也。
This is what makes one grow teeth at eight months, then lose them [for new ones] at the age of eight.
」賢者不然，精化填盈，後傷時之不可遇也。
Then at sixteen, twice age eight, one’s reproductive essence first begins to flow.
不見道端，乃陳情欲以歌。
A female grows teeth at seven months, then loses them at seven years; then at fourteen, twice age seven, her reproductive essence first starts to flow.
詩曰：「靜女其姝，俟我乎城隅，愛而不見，搔首踟躕。
The unworthy allow their sexual desires to run rampant the moment their reproductive essences begin to arrive, so they act perversely and create disorder.
」「瞻彼日月，遙遙我思。
Thus, a passage in the Odes says, “This sort of man exists, / Who longs to have a mate; / His word cannot be trusted— / He is ignorant of fate.” The worthy are not like this; when their reproductive essences are fully formed, they grieve that the times they live in are not propitious.
道之云遠，曷云能來！
If they do not see a way of proceeding that conforms with the Way, they put their amorous feelings into lyrics.
」急時之辭也。
甚焉，故稱日月也。
As is said in the Odes, “Of fair girls the finest, / Beneath a nook awaits me; / Reluctant, she stays hidden; / I scratch my head and pace,” and in another place: “I gaze at sun and moon above, / I think of what is far away. / The way, alas, is long; / How, alas, shall I return?” The feeling here is intense—that is why the sun and moon are invoked.