《梦溪笔谈·补笔谈卷二》
如岁差之类，直到近世才发现，这当然也就没有以今变古的嫌疑。凡是太阳出没一次，就叫做一日；月亮亏盈一遭，就叫做一月。
然事固有古人所未至而俟后世者，如歳差之类，方出于近世，此固无古今之嫌也。凡日一出没谓之一日，月一盈亏谓之一月。
For example, the solstice was only discovered in recent times, and of course there is no suspicion of changing the ancients today. Every time the sun rises and sets, it is called a day; and every time the moon wanes and waxes, it is called a month.