Joint refers to the connection between strokes in running script or cursive script, for example, the word "Lian" can be completed in one stroke; Echo, echo every stroke before and after. The so-called broken pen meaning connection, such as the two points above the word "beauty" is the echo point. Pick one and leave one, so that the left point is low, the right point is high, and the left point is left. Even if there is no connection between the left point and the right point, it is left and right, with a sense of rhythm and coherence. Every word is a world, reasonable and beautiful.
Of course, there is also the echo of the structure, the echo of the whole article and so on. It contains all the knowledge and truth in the world! It depends on which angle and level you look at it.