前言毛主席教导我们:“人类的历史,就是一个不断地从必然王国向自由王国发展的历史。这个历史永远不会完结。……在生产斗争和科学实验范围内,人类总是不断发展的,自然界也总是不断发展的,永远不会停止在一个水平上。因此,人类总得不断地总结经验,有所发现,有所发明,有所创造,有所前进。” Foreword Chairman Mao taught us: “Human history is a history that constantly develops from the necessity kingdom to the freedom kingdoms, and this history will never come to an end .. In the production struggle and scientific experiments, mankind always develops continuously, Nature is always evolving and will never stop at a level. Therefore, mankind always has to sum up his experience, discover something, invent something, create something, and make progress. ”