《论衡·卷六·雷虚篇》
黄河中的图、洛水中的书，都是天作的，人一读就知道它的意思。
河图、洛书，天地所为，人读知之。
The pictures in the Yellow River and the books in the Luo River are all made by heaven, and people know what they mean as soon as they read them.