Lang Yi Predicts the Future
 
Lang Yi, courtesy name Yaguang, lived in Anqiu of Beihai in the Han Dynasty. His biography can be found in the Book of Later Han.
 
Lang Yi’s father, Lang Zong, was very good at predicting the future by observing celestial phenomena. During the years of Emperor An (106 – 125 AD), the emperor appointed Lang Zong as magistrate of Wu County. There were frequent, sudden windstorms at the time. Lang Zong predicted that there would be a fire in the capital city. He wrote down the time of the fire and assigned people to keep watch. At the time he predicted, there was, indeed, a fire in the capital city. When the emperor learned about this, he wanted to appoint Lang Zong to a higher position. Lang Zong refused since he believed it was shameful to exchange his foretelling ability for personal benefits. Lang Zong left the county office that night and never became an official again.
 
Lang Yi, who was a great predictor as well, learned from his father. During the years of the Shun Emperor in the Han Dynasty (125 – 144 AD), there were many natural disasters and abnormal weather phenomena. When the emperor called on Lang Yi, Lang Yi wrote admonitions to the emperor, telling him that natural disasters were the means by which gods reproached emperors. They were telling the emperors to correct their mistakes in governing the nation. Lang Yi sincerely suggested to the emperor that he listen to his officials and examine himself every day in order to rid the natural disasters. Lang Yi particularly pointed out how the government was squandering funds, not empowering capable officials, punishing its citizens too severely and that officials were mired in laziness. He predicted there would be an earthquake at the turn of summer, and flooding water would come from the cracks in the ground.
 
After reading his admonition, the emperor sent a secretary to criticize him. Risking his own life, Lang Yi wrote another letter to the emperor, explaining in detail how natural disasters were related to government policies, and listing ways to eliminate natural disasters. He even noted four things that would benefit the country. Lang Yi wrote that if the emperor adopted his suggestions and changed the policies immediately, it would rain on the first day of summer to benefit the crops. He was willing to accept the capital penalty if his prediction was inaccurate.
 
This time after reading the letter, the emperor appointed him to a high-ranking official position, but Lang Yi refused to accept the appointment, claiming he had health problems. He left the capital city and went back to his hometown.
 
The emperor did not examine his own mistakes as Lang Yi suggested, and the policies were not changed, either. That year there was an earthquake in April, which caused a subsidence of the earth; there was no rain at all in the summer, causing severe drought. In the fall, the nomadic Xianbei people of the north invaded Mayi City. The next year the Qiang people of the west invaded Longxi. All these were exactly in line with what Lang Yi had predicted. This time the emperor called Lang Yi for an official appointment again, and Lang Yi refused again.
 
A celestial phenomenon is an indicator of what will happen in the human world. Unusual phenomena will appear, and natural disasters will happen as a warning if the human world operates against the will of heaven. If humans do not correct themselves immediately, more severe natural disasters will happen as punishment. Ancient Chinese people learned from divine culture. There were many wise men who could make predictions by observing celestial phenomena. They conveyed heaven’s will to the public. In ancient China, some special government branches—such as Sitianjian and Qintianjian—were in charge of predictions.
 
人有过天示警　不归正天谴至
 
郎顗，字雅光，是北海安丘人，《后汉书》有传。
 
郎顗的父亲郎宗，字仲绥，擅长观察天象以预测世间吉凶。汉安帝时，郎宗被任为吴县令，当时经常突然刮起暴风，郎宗预测到京师将要发生火灾，于是将时间记下来，派人等候着，结果真如他所预测的一样京师如期发生了火灾。这件事后来被皇帝知道，想召他为博士，但郎宗认为以此换取功名是可耻的，于是连夜将印绶挂在县衙离去了，从此终身不再当官。
 
郎顗继承父业，也精通观天象知人事。汉顺帝时，经常发生灾害和异常现象，朝廷征召郎顗，郎顗于是献上奏章，说天垂异象，地现灾兆，这是上天在责怪帝王，要他们修正自己的行为德操，使政事回归正常。其中言辞恳切的希望皇帝能听取意见，每天多加反思，反省自己的过错，务求消除这些灾祸，并且引经据典的指出了当时朝廷奢侈放荡、不重用贤士、刑罚过重、官员安逸放纵等弊端，还明确指出立夏之交时会发生地震，有地面裂开洪水涌出之类的灾害。
 
皇帝看了奏章后派尚书责问于他，郎顗冒着触犯忌讳被杀头的危险再次上书，详细阐述了各种天象和灾祸与世间政事的关系，并且一一提出了消除化解灾祸的办法，还提出了四件有益国家的事，希望朝廷能够及早实施，并指出如果朝政能够马上改善的话，立夏之交会有及时雨，否则自己愿意以死谢罪。
 
皇帝这次看了奏章后将他特诏为郎中，郎顗声称自己有病没有接受，离京回到了自己的家乡。
 
皇帝并没有向上天反省自己的过失，朝政的改善也没有起色。这年的四月果然发生了地震，并发生地陷；夏天没有降雨，发生大旱；秋天鲜卑入侵马邑城；第二年，西羌入侵陇西，这都与郎顗先前预言的差不多。此后朝廷又去征召他，郎顗仍旧没有接受。
 
天象的变化会对应世间出现变化，如果世间发生违背天意之事，那么上天就会现异象或降灾祸以示警，如果不能及时归正过失，那么上天便会降下更大的灾祸以示惩戒。受神传文化薰陶的古人敬天知命，有很多能够洞悉天象预知人事的智者，他们向人们传达着上天的信息和意愿，朝廷中的“司天监”、“钦天监”等就是这样的专门机构。