From the central point of view, decide the choice of materials, discard materials that have nothing to do with the theme or have little to do with it without regret, although these materials have been collected painstakingly. If you lose something, you can gain something. A piece of wool is precious inch by inch, so it is difficult to cut it and it is impossible to sew clothes that fit. For ready-made clothes, unnecessary parts must be cut off. Therefore, we must always bear in mind that materials are only used to form the arguments of our own papers. Without this, even the best materials should be abandoned.