宇宙間的物理变化,常有一定的規律,如地球绕太陽旋轉,如物体之热涨冷縮。这些規律有簡單的,也有複雜的。簡單的規律很容易為人們在生活体会中所认識,由認識而掌握了這些規律,使它為人們所利用。这是人們与自然力量的斗爭,這是科學發展的一部份。但是複雜的規律,變化多端,捉摸不定,常不是人們在简單而短促的生活體會中所 The physical changes in the universe, often have certain laws, such as rotation of the Earth around the sun, such as the heat of objects shrinkage. These laws are simple and complex. Simple rules can be easily understood by people in their daily life, knowing these rules and making them useful to people. This is a struggle between people and the natural forces, which is part of the scientific development. However, the complex laws, changing and unpredictable, are often not the simple and short-lived experience of people