His talk was so unintelligible that I couldn't understand what he was saying at all.

The King of Na gold seal played an important role in Japanese history.

He is writing a thesis on fluid dynamics.

He is known as an expert in palaeoclimatology.

I am majoring in econometrics at university.

This ancient proverb, 'know the other side and yourself, and you will not be in danger in a hundred battles', teaches us the importance of understanding ourselves and others.