In fact, if you are not majoring in philosophy or mathematics, you can simply understand the landlord's question. You need a thick book to dig deeper. Finally, when you finish learning this book, you will find that there is no final answer yet. Even I am studying it myself. Your question is called "epistemology" or "epistemology" in philosophy. As its name implies, this subject is devoted to the study of people's cognitive style and its possible results.
Your teacher's words mean that, personally, the result of cognition is that truth is ultimately unattainable, but human beings can reproduce and constantly realize that there is endless knowledge to reach the truth. I wonder if your teacher is a philosophy teacher? Alas, this teacher is misleading you because of his own confusion!
In the history of philosophy, there are mainly agnosticism and agnosticism, and your teacher actually introduced agnosticism later. In fact, most philosophical schools, including Ma Zhe, support agnosticism. Therefore, the reference book you buy, if it is not a professional college textbook, will certainly only simply guide you to understand agnosticism.
Let me briefly explain your doubts and say some answers to questions that you can't find in general information.
The core issues of philosophy are undoubtedly "Who am I", "Where do I come from", "Where do I go" and "What is the origin of the universe". . . . . . The question of epistemology is just a possible guess to answer "I want to go there", in other words, it is to ask people the unique nature that distinguishes this advanced animal from animals-the relationship between thinking and truth. In the early days, human beings mainly maintained an attitude of admiration for nature, and their thinking on some issues was relatively simple. At that time, truth was basically equivalent to faith. In the so-called Axis Age in the history of philosophy, great thinkers appeared in Greece, China and India, who put forward various ideas and theories. I mentioned faith before, and you may ask, what does this have to do with our problem? Primitive people's way of thinking is mainly based on the worship of hypothetical gods, lacking rational and logical reasoning, so their interpretation of the universe is mainly based on faith. During the axial period, thinkers began to separate faith from truth by reason, and gave their own theories a certain logical explanation, so truth and faith began to be different. In Greece, since Socrates, he boldly proposed to know himself first. He put forward transcendentalism, thinking that people knew the universe originally, but later forgot it, so people learned and gradually recalled what they had forgotten. When someone argued with him, he found a child who knew nothing. By asking questions, the child actually wrote the Pythagorean theorem. When Plato arrived, he thought that there was no real world at all. He has several famous metaphors. There is a cave metaphor about cognition. He believes that human cognition is actually an illusion. Of course, people's limited senses can't finally know the world. That is to say, if people's cognitive process is like a group of people tied in a cave, facing the wall, they can only see the shadow of the sun on the outside wall and can't turn around, so they mistake these images for real existence. When someone can stand up and turn around (such as a philosopher) and see the scene behind him, he finds that what everyone mistakenly thinks is actually just a shadow. In addition, there is "skepticism" represented by Pyrrho. The most important thing in India is the founder of Buddhism, Sakyamuni. Buddhist philosophy is a relatively complex system. Cognitive, I think it advocates epiphany agnosticism (not so many children and grandchildren, hehe). Sakyamuni told the boy that there was an "arrow metaphor" story, and Zhuangzi of China also famously said, "My life is limited, but my knowledge is also limited, so that there is no boundary with it." In fact, the meaning is the same as the first half of what your teacher said, and I agree with it.
With the development of philosophy in modern times, the problem of cognitive theory is mainly based on the discussion of ontology. Mainly from Descartes, Hume to Kant. Descartes was the first person to prove "noumenon" by rational and rigorous logical reasoning, so his "I think, therefore I am" is also called the awakening of subjectivity. This marks the beginning of the era of understanding truth through strict logical reasoning. Through this way of thinking, Hume, a famous representative of empiricism, put forward the famous Hume paradox, that is, the black swan paradox. This paradox can be said to vividly show that human cognition is limited and the universe is unknowable. Kant, on the other hand, integrated the foundation of predecessors and proposed to understand existence in a certain time and space background. In modern times, it is a more complicated system. Generally speaking, in the history of philosophy, the problem of cognition presents a pattern from simple belief to logical reasoning and then back to belief. I mentioned "ontology" several times, and ontology is actually the origin of the universe. For example, Ma Zhe believes that the origin of the universe is matter, and its fundamental attribute is eternal motion. Then the answer to the question is obvious. Since everything is an eternal movement, truth is out of reach. Unlike what your teacher said in the second half of the sentence, human beings can't exhaust their knowledge for future generations. Children and grandchildren can live forever, which just reflects the eternal movement of the universe. However, if knowledge is exhausted one day, it will be troublesome, and you will find contradictions through logical reasoning. It shows that people at that time already knew everything, and they could do it once and for all, and even the process of cognition itself could stop. What's the difference between stopping and dying? Is it still called eternal movement?
To sum up, so in general, there is no clear answer to the question of cognition, whether human beings can exhaustively know the world. This answer seems ridiculous, but it is actually very subtle. This is like the word philosophy itself, which comes from Greek and translates as "love wisdom". In fact, on the day when philosophy was born, philosophers found that they were pursuing questions that had no answers at all. Since they can't pursue the answer, let's call it love for wisdom! From that day on, philosophy was born. If you can't pursue it, why are you still pursuing it? Perhaps, this is all the dignity that we human beings are different from animals and born as human beings!