《论衡·卷十八·自然篇》
有人问： 人生在天地之间，天地没有意识，人承受了天性，也应当没有意识，而人却是有意识进行活动的，这是什么道理呢？ 
问曰： 人生於天地，天地无为。人禀天性者，亦当无为，而有为，何也？ 
Someone asked: People live between heaven and earth. Heaven and earth have no consciousness. Man has inherited nature and should not have consciousness. However, man has consciousness and carries out activities. What is the reason?