Volume 6: The Meeting of Two Heroes, Chapter 15: Davos's Academic Lecture

For this very reason, Daonia was a land that Greek doctors aspired to visit.

Davos pried open the outer skin where the model’s lower jaw and neck joined, revealing the passage inside. “Everyone, please look—the openings of the mouth and nose merge here, then split into two separate passages—”

He pointed to the soft tubes made of tanned leather. “We all know the nose is for breathing air, but the mouth both breathes air and takes in food and water. Air and food each follow their own path. Through long-term observation by the doctors of the School of Medicine, they believe this passage carries air, and they call it the trachea. The other passage behind it carries food and water, and we call it the esophagus. Everyone, feel the lower part of your own neck—the hard, uneven bump beneath the skin is the trachea.”

The foreign doctors below the podium actually reached up to touch their own necks, trying to feel what Davos described.

“Some of you may wonder: since the openings of the esophagus and trachea are connected, wouldn’t food and water easily enter the trachea?” As Davos spoke, he noticed many nodding, so he smiled and continued. “In fact, this is almost impossible. There is a very soft piece of cartilage at the opening of the trachea. When we swallow, it automatically covers the opening and prevents food or water from entering. If you are interested, after the meeting you can come up and see for yourselves. Under the guidance of the doctors, our Daonian craftsmen have used their exquisite skills to build this human model with remarkable accuracy. Just don’t break it—this model is the School of Medicine’s greatest treasure. No amount of money could buy it! Am I right, Helpus?”

“Yes, Teacher Davos. Normally we only use it during teaching sessions, and we generally don’t let anyone touch it,” Helpus said with a smile.

Hearing this from Davos and Helpus, the foreign doctors grew eager. They stood up one after another, craning their necks toward the human model beside Davos, causing a bit of commotion.

Davos continued, “I heard that it was the School of Medicine’s young doctor, Critos, who discovered this cartilage. To do so, he even dissected live pigs and sheep, carefully observing the movement and mechanism of this cartilage. Is that correct?”

“That’s right,” Helpus nodded.

“Is he here today?” Davos asked with a smile.

“He is.”

“Then please stand up, Doctor Critos, so everyone can get to know you.” Davos spoke loudly, smiling.

Critos stood up shyly under the nudging of his colleagues.

“Let us thank Critos for this important discovery with warm applause!” Davos started clapping first, and soon the entire hall burst into applause. Some of his colleagues even whistled excitedly.

Critos was both nervous and thrilled.

Lycasus watched Critos standing up ahead with envy: this doctor, who seemed not much older than himself, was shyly accepting the applause of the whole hall. When would he himself be able to make a name across Magna Graecia like Critos, instead of being a mere apprentice day after day, like a servant?

“Critos, I look forward to you making more discoveries in medicine and achieving even greater accomplishments!” Davos encouraged him warmly.

A young man encouraging another young man in the tone of an elder—the scene might have seemed ridiculous, but most of the doctors present did not think so. Critos, meanwhile, was so stirred that his chest heaved rapidly. “Yes… yes, Teacher Davos!”

After Critos sat down, Davos continued. “If you sometimes eat carelessly and suddenly choke and cough, it’s because the cartilage failed to cover the trachea in time, allowing food to enter the trachea. If a mother brings an infant to you for treatment, saying, ‘The baby can’t stop choking while drinking milk,’ it might also be for this reason…”

The foreign doctors silently memorized what Davos said, comparing it to similar cases they had seen before.

“Air follows the trachea into an organ. After many dissections, the Daonia School of Medicine calls this organ the lung.” As he spoke, Davos pried open the human model’s chest, removed the left lung carved from wood, and showed it to the audience.

“The School of Medicine’s dissections found that we each have two lungs, one on the left and one on the right. They are like the pig bladders children play with. When you inhale, air enters and the lungs expand; when you exhale, air leaves and the lungs shrink. You may think it strange: air enters the lungs from the mouth and nose, then leaves the lungs through the mouth, making a full circle back to the start, seemingly meaningless. But I tell you, our bodies are the most precious gifts the gods have given this world. They are extremely wondrous and never do anything pointless!”

Davos looked around at the doctors below the stage. Seeing that they were listening with full concentration, he said earnestly, “The School of Medicine, after many dissections of corpses, discovered that after the trachea enters the lung, it keeps branching into ever smaller passages, like a tree branching into smaller branches. In the end, how big do you think the smallest tracheal tubes are?”

Davos pulled a hair from his head and said, “About this big! And at the end of these tiny tracheal tubes, what is there? Who can tell me?!”

At that, a young Daonian doctor stood up: “Blood vessels! During dissection, we found many equally tiny blood vessels interwoven with these tracheal tubes. These tiny blood vessels come from the continuous branching of two large blood vessels from the heart…”

“Then what do these two large blood vessels from the heart do?” Davos continued.

“They come from different parts of the heart. One is responsible for pumping blood to the lungs, and the other for collecting blood back from the lungs.”

“What other obvious differences are there?”

“Um… the one that pumps blood out is a single blood vessel, while the one that collects blood back is two blood vessels…” the young doctor answered hesitantly.

“That is a difference. Anything else?”

“Uh…” The young doctor’s face turned red, and he couldn’t answer.

“Thank you for your answer. What is your name?”

“Strobus of the Daonia School of Medicine.”

“Thank you for your excellent answer. Well said!”

Strobus, who had been slightly dejected, broke into a smile at Davos’s compliment.

“Everyone, air goes into the lungs in a circle and then out again; blood goes into the lungs in a circle and then back to the heart. If nothing happened during this process, our bodies would be so boring that they would endlessly engage in meaningless activity. Is that possible?!” Davos posed the question, leading the audience into contemplation, and then he answered decisively: “Of course not! Air and blood must undergo some wondrous reaction inside the lungs, only we cannot see it with our naked eyes—just as we cannot see what it is that causes our wounds to become infected. So what is that reaction? And how important is it to our bodies?”

Upon hearing this, the doctors showed great interest. As they thought, they perked up their ears to listen to what Davos would say next.

Davos smiled. “Although I do not know exactly what reaction occurs between blood and air, we can detect its existence through certain phenomena. Helpus, have you ever carefully observed the blood inside a human or animal body? Have you noticed anything different about blood?”

“Blood?” Helpus fell into thought. Truth be told, Davos had not informed him of the topic of today’s lecture in advance. Like the others, Helpus had taken transparent air for granted and never deeply considered this aspect. Moreover, in the past two years, he had been busy as head of the Ministry of Health, also serving as director of the Thurii Hospital and dean of the Daonia School of Medicine. With increased administrative duties, he had lacked time for medical research.

Beside him, Stesicondas was also deep in thought.

“Oh!” Someone suddenly remembered something and shouted, “It’s the color! The color of blood!”

Davos fixed his gaze and saw that it was Critos who had spoken. He gave an appreciative look at this thoughtful, innovative young doctor, then quickly withdrew his gaze. “That’s right—it’s the color of blood! Doctors of the School of Medicine, as long as you have performed live animal dissections on this topic, you will have found that blood, which originally has a dull color, turns a bright red when it enters the lungs and is brought back to the heart by the other blood vessel. Inside the lungs, only air and blood flow. So it must be that something in the air enters the blood, causing the change in blood color! And this thing… this invisible thing that enters the blood—what effect does it have?”

Helpus, Stesicondas, Critos… all the doctors, including Lycasus, now stared intently at Davos. Each held their breath, afraid of missing a single word.

Davos’s expression turned serious. “We have noticed that the blood returning to the heart is then pumped throughout the body. The bright red color of the blood manifests on our bodies. Our lips are red, our fingertips are red, our faces turn red after exercise… When we see a person with these features, based on years of medical experience, we can easily judge that this person is healthy and full of vitality. And sometimes we encounter patients whose lips are purple-black, the tips of their limbs are blackened, their faces are ashen, and they walk unsteadily… We can also easily judge that this person is ill, and gravely so. Is this not the difference between blood that has been mixed with this thing from the air and blood that has not, manifested on the body? Can we not consider that this thing is as indispensable to the human body as food, making us healthy and energetic? Can we not make the inference that for such patients with purple lips and blackened fingertips, there is a problem in one of the pathways—the trachea, or the lungs, or the blood vessel entering the lungs, or the blood vessel returning to the heart—so that this thing from the air ultimately fails to reach the whole body through the bloodstream?!”