What is there to say about the emergence of new things and the demise of old things?

It can also be said to be development.

(1) Development is the upward movement and change of things, so new things are not created out of thin air, but on the basis of old things, which are connected with the past. "Bring forth the old and bring forth the new" shows the connection between the old and the new.

(2) Development is the emergence of new things and the extinction of old things. In this sense, development means "breaking the old and establishing the new". However, the new thing does not completely deny the old thing, it just abandons the negative, outdated and decadent things in the old thing and absorbs and develops the positive and reasonable factors in the old thing.

3) It is one-sided to think that development is a new thing and completely deny the old things.