"Wei Jing" is a name.
The ancients said, "There is no limit to learning the sea, but it is hard to make a boat." It means that hard work is the key to learning. Endless learning is necessary for every aspirant. If people want to make continuous progress, they have to live and learn. You can't be bored with your studies. This sentence of Han Yu is intended to tell people that there is no shortcut and no boat to sail on the road of reading and studying. If you want to learn more and more knowledge in the vast mountain of books and learning, "diligence" and "concentration" are two essential and the best conditions.