《淮南子·说林训》
占卜者拿着龟壳，占筮者拿着蓍草，而要询问占卜的方术，这哪里是他们该问的呢！
卜者操龟，筮者端策，以问于数，安所问之哉！
The diviner holds the tortoise shell, the diviner holds the yarrow stalks, but wanting to ask about the methods of divination, where would they ask about this!