《论衡·卷二十六·知实篇》
贤圣的才能，是都能先知。他们的先知，是运用各种术数，或者是善于估计和巧妙的推算，并不是圣人凭空就知道的。
贤圣之才，皆能先知；其先知也，任术用数，或善商而巧意，非圣人空知。
The talents of the sage and virtuous are to be able to foretell. Their foretelling is the application of various techniques, or the skill of estimation and clever calculation, not something that the sages know out of thin air.