Learning is like sailing against the current. It is Liang Qichao's famous saying that if you don't advance, you will retreat.

If you don't advance, you will retreat. It means sailing against the current. Metaphor means that if you don't work hard, you will retreat. It is also a metaphor for doing things with resistance and having to work hard. Source: Liang Qing Qichao's "Speech at the Welcome Meeting of Shanxi Ticket Merchants": "The old man can keep it, and he has gone! However, I think that in the world, it is like sailing against the current. If you don't advance, you will retreat. "