With the help of the phenomenon that fresh water is injected into the pond, this sentence means that we must constantly accept new things in order to keep our thoughts active and progressive.
Random thoughts on reading is a poem by Zhu, a philosopher in the Song Dynasty. Full text: When half an acre of square pond opens, the sky is high and the clouds are light. Why is the water in the pond so clear? Because there is inexhaustible living water for it.
A half-acre square pond is displayed like a mirror, in which the brilliance of the sky and the shadow of floating clouds move together. Why is the water in that square pond so clear? It is because there is an inexhaustible source to continuously transport living water for it.
Appreciation of the whole poem:
The poet then opened his eyes and looked from a distance. Finally, he saw the "source" of "Fangtang" and found the answer. It is precisely because "Fangtang" is not passive water, it has inexhaustible "source" and continuously delivers "living water" to it.
This "square pond" will never be exhausted, stale, dirty, deep and clean because of the continuous input of "flowing water from the source". "Qing" can not only embody "sky and clouds", but also embody such detailed modality as "sky and clouds" and "* * *". This is the image and ideological significance of this little poem.