Wake Forest University

Traditional:

64
　　問學者云：「古人排十二時是如何？」諸生思未得。 先生云：「『志』是從『之』，從『心』，乃是心之所之。古『時』字從『之』，從『日』，亦是日之所至。蓋日至於午，則謂之午時；至未，則謂之未時。十二時皆如此推。古者訓『日』字，實也；『月』字，缺也。月則有缺時，日常實，是如此。如天行亦有差，月星行又遲，趕它不上。惟日 ，鐵定如此。」又云：「看北斗，可以見天之行。」夔孫 。
Translation:
[Zhu Xi] asked his students: How did the ancients arranged the twelve (times =) watches of the day? None of them got the answer. The master said,"The character 'zhi' is composed of 'zhi'and 'xin' that is, the place to which the xin (heart) goes (zhi). The ancient character 'shi' is from "zhi' and from 'ri' which means the place to which the sun (ri) goes (zhi). That is just to indicate that when the sun arrives at wu, then it is known as the wu watch. When the sun arrives at wei, then it is known as the wei watch. All the twelve watches of the day are named in this way. The ancients explained the derivation of 'ri' as 'full, complete,' and explained 'yue' as 'que' (having something missing). The moon has times at which it is not whole, but the sun is always whole, which fits their description. Another instance would be the way the movements in the heavens have discrepancies, the movements of the moon and the stars are also too slow and so are unable to keep pace with the sun. It is only the sun that is unfailingly dependable." He also said, "Look at the Big Dipper, and you can observe the movement of heaven." Kuei-sun
Commentary:
There are no markers in the daytime sky, so it seems a little odd to speak of the sun arriving at such-and-such a point unless Zhu Xi actually had the idea of a sun dial in mind. It would be natural to divide the semi-circular dial around the vertical rod in the middle into equal spaces. When oriented to north as determined by the position of the pole star, the sun's shadow at noon (wu) would have been pointing directly north. To divide the entire day into 12 equal watches one could not entirely depend on the sun's shadow, of course. The stars that are seen in the night sky, and their positions in that sky at different hours of the night, vary according to the time of year at which observations are made. But it is still possible to reckon time by the night time sky..
The outer planets can seem to change direction as they move across the background of the stars. Imagine that a turtle was moving along the out-of-bounds line on the long axis of a basketball court. A person comes in and starts walking down the center of the court. He can see the seat numbers behind the turtle. When he first enters, because he is viewing the turtle from behind and also sees it to his right, he sees seat number 300 in line with the turtle. As he comes abreast of the turtle he sees seat number 200 in line with the turtle, a little while later he sees seat number 100 in line with the turtle. That is because he has passed the turtle. To him, the turtle appears to be moving backwards. When he comes near the end of the basketball court, his exercise for the day being over, he slows down for a while. At some point he looks back and observes that seat number 400 is now in line behind the turtle, i.e. it seems to him that the turtle has stopped moving away from the far end of the basketball court and has begun to move toward it. That perceptual effect is similar to what happens when somebody observes Saturn from earth. At some point it seems to slow down, to stop, to go backwards, and then resume its forward progress, all because we started out behind it and then passed it on the inside.
Without knowing that the earth is in orbit around the sun and also revolving around its own axis, it is very difficult to understand some of the observed motions of planets. Not only are planetary movements seemingly inconsistent at some times, but without knowing that the same longitude on earth is not necessarily going to be experiencing midnight after the earth has made one complete revolution around the sun, it must have seemed odd to the people of Zhu Xi's time that the night sky was different on successive solar New Year's Days.
By giving primacy to the solar day and the motions of the sun, calling the sun complete and describing the moon as missing something most of the time, Zhu Xi is giving tacit primacy to Yang and secondary position to Yin, which in an ideological way gives support to the social primacy of men over women.