《论衡·卷三·物势篇》
再说，金、木、水、火、土五种气相互残害，有血动物相互取胜，制服对方，又在什么地方有过验证呢？
且五行之气相贼害，含血之虫相胜服，其验何在？
Moreover, as to the five elements, metal, wood, water, fire, and earth, and the way they conquer each other, and the carnage between bloody animals and their victory over others, where has it been witnessed?