Take a cup and pour water into it, and keep pouring. . . . . Wait until a glass of water is completely filled, that is, the height of the water surface is equal to the height of the cup mouth ~ don't stop, keep pouring, but pay attention to pouring slowly. At this time, you can find that the water level in the cup has exceeded the height of the cup mouth, but the water will not leak down. Until you can't stand adding water to the surface, the water above the cup mouth suddenly flows down.
This property of water is called tension.
Tension in literature is a feeling, which is difficult to explain clearly in words. If you understand this experiment, you may have some understanding by comparing it with the literature.