After Li Zhi entered the academy, he was taken by several children of Da Niu.

After the class in the academy was over, Li Zhi returned to the horse circle and pestered Li Zheng, who was cooking, "Li Zheng, Brother Niu said that light can be refracted by light. ”

Li Zheng nodded slightly, "It has always been refractive." ”

Li Zhi asked again: "Then why is the scene reflected behind the small hole looking reversed?" ”

While boiling the fish soup, Li Zheng explained: "That's the small hole imaging, and the other is the refraction of light, which are two problems. ”

Li Zhi continued: "Brother Da Niu is so powerful. ”

Li Zheng took out a bowl of fish soup and put it on the table, and then he wanted to roast the braised pork.

Da Niu should have seen the course of small hole imaging, which was indeed written in his own book.

Li Tai stepped on the meal and came back, and every time he came back, Li Tai was covered in sweat, and he was willing to sit down to eat after taking a bath.

After the meal, Li Zheng told Li Zhi about why the small hole imaging is reversed.

A piece of paper draws a circle representing the small hole, Li Zheng drew a diagonal line and said: "His Royal Highness the King of Jin, first of all, the light is illuminated in a straight line, and if you want the light to refract, you need a condition for optical refraction, so there is no refraction condition after the small hole imaging ray passes through the small hole, or is it a straight line, right?" ”

Li Zhi nodded ignorantly, "I kind of understand, the straight line and the straight line are intertwined." ”

Li Zheng drew another line, running through the small hole from the footsteps of the portrait, diagonally upward, "so the portrait will be reversed, and the light will not meet the refraction conditions, so he is also straight in the small hole." ”

"I understand now." Li Zhi nodded.

Li Tai sat aside and asked, "So how do you make light refract?" ”

"Mirrors and water." Li Zhi immediately replied, "Brother Da Niu told me. ”

Li Zheng pinched Li Zhi's chubby face and said, "His Royal Highness King Jin has learned well. ”

That night, Li Zhi had already slept, and when he saw Li Zheng sitting by the horse ring looking at the starry sky, he stepped forward and asked, "Can't you sleep?" ”

Li Zheng said with a melancholy expression: "His Royal Highness King Wei, when did you say that your father and the emperor would give me Yulu." ”

Li Tai really didn't want to answer Li Zheng's question, thinking to himself when his father would give you Li Zheng and Lu, how do I know, are you Li Zheng so rich and still lacking those Yulu?

After coming to the thatched house to relieve himself, Li Tai washed his face again.

Li Zheng often looks at the starry sky in a daze.

Li Tai has become accustomed to such things.

Sitting next to Li Zheng, Li Tai said: "You like to watch the stars at night? ”

"Does His Royal Highness King Wei want to watch it together?"

Li Tai glanced up at the stars in the night sky, "What do you mean by such a star?" ”

Li Zheng shook the folding fan in his hand and said: "It means that the Tang Dynasty will be prosperous in the next hundred years." ”

"Really? That's great. ”

It seems that this sentence is very useful to Li Tai.

Li Zheng continued: "His Royal Highness King Wei, do you know? No matter how the world changes, the stars in the sky will not change for a long time, and you see the moon will accompany us for many, many years, thousands of years, or even ten thousand years. ”

An eternal starry sky? Li Tai looked at Li Zheng in surprise, "Li Zheng, aren't you comprehending some heaven and earth avenue?" ”

Li Zheng disdainfully smiled, "If you can comprehend the Great Dao of Heaven and Earth by looking at the night sky, this astronomer from all over the world should become immortals." ”

"What is an astronomer?"

"His Royal Highness the King of Wei can be understood as one of the hundred sons."

Li Tai looked suspicious, "Is there this one among the hundred sons?" ”

"Possibly." Li Zheng nodded.

"Why has this king never heard of it?"

"Because they're all very low-key." Li Zheng turned his head to look at Li Tai, "Isn't His Royal Highness King Wei going to sleep yet?" I have to go to the construction site early tomorrow morning to repair the road. ”

Seeing that Li Zheng didn't want to say more, Li Tai went back to sleep.

Li Zheng still looked at the stars in the sky, the ancient night sky was very beautiful and very clean.

The horses in the horse pen snorted, and the snoring of Li Tai and Dahu was heard in the distance, and Li was lying on the chaise longue and turned over to sleep, and he had to hurry up and make the sofa.

As soon as he got up the next day, Li Zheng felt that all the bones in his body were rebelling, and this was the consequence of sleeping on a chair.

Seeing that Li was walking with his waist on his back, Dahu hurriedly said, "What's wrong with Zhonglang General?" ”

"Nothing." Li Zheng said to Dahu: "It's just that I didn't sleep well last night, and it will be much better if I move for a while, have you fed the horse?" ”

"It's been fed." Dahu said.

When Wang Ding came to Jingyang again, Li Zheng knew that Li Shimin couldn't wait.

"Princess, please take a seat." Li Zheng said invitingly.

Wang Ding sighed with emotion, "County marquis, county marquis, there has been no news until now after three months, which can make Your Majesty wait." ”

"Isn't it time yet?" Li Zheng said nonchalantly.

Wang Ding said, "There are still ten days." ”

"Ten days is the sky, it will definitely be made." Li Zheng patted his chest and said, "It's not a compound bow, it's not easy to make a three-edged thorn." ”

"Simple ......," Wang Ding put down the teacup in his hand, "Since it is simple for the county marquis, why do you have to put it off again and again." ”

Li Zheng refilled Wang Ding with another cup of tea and said, "Does Wang Gonggong think I'm smart?" ”

Wang Ding nodded, "You are very smart." ”

"That's it." Li Zheng continued: "Then dare to ask the prince how much is five plus seven plus eight plus nine plus ten......"

"It's equal to ......," Wang Ding counted his fingers for a long time, unable to speak.

"Equal to thirty-nine." Li Zheng said.

"It turned out to be thirty-nine." Wang Ding wiped the sweat from his forehead and replied.

"There are some things that I think are simple and what the prince thinks are simple, I think the simple things, the prince must not be simple, and the things that the prince thinks are not simple must be simple for me."

Wang Ding covered his forehead and said, "County marquis, wait, the old slave is a little messy now." ”

Li Zheng continued: "All in all, what I said is simple to make a three-edged thorn, but it is very difficult for the prince. ”

"Is that so?"

"So the princess, please go back and report to Your Majesty."

Only half a day after Wang Ding went back, Li Zheng watched the old eunuch come to Jingyang again.

"County Marquis, Your Majesty said that we should wait in Jingyang and wait until the new weapon is born"

Looking at Wang Ding in compromise, Li Zheng sighed helplessly, "Your Majesty is really impatient." ”

Wang Ding spoke: "Your Majesty is very concerned about new weapons. ”

The old eunuch's smile was indeed a little oozing.

Wang Ding still said calmly: "County Marquis, Your Majesty wants to hold the imperial examination, but now there are many difficulties, do you have any way to do this?" ”

Li Zheng casually knocked on the melon seeds and said, "What can I do." ”

"The prince is sitting here, and I'll go to the village to have a look." Li Zheng stood up and pointed to a pot of melon seeds on the stone table and said, "The prince is free." ”