The Recorded Sayings of Chan Master Huangbo

Chan Master Huangbo said: 我此禅宗，从上相承以来，不曾教人求知解。只云学道，早是接引之词，然道亦不可学。情存学解，却成迷道……第一不得作知解。

He also said: 古人心利，才闻一言，便乃绝学，所以唤作绝学无为闲道人。今时人只欲得多知多解，广求文义，唤作修行。不知多知多解，翻成壅塞。《黄蘖传心法要》(Essentials of the Transmission of Mind by Huangbo)

Being given a single green leaf and then digging out a whole nest of sweet potatoes—that is true realization through awakening. Asking others for a huge pile of sweet potatoes while being unable to see even a single leaf—that is sweet potatoes dug up by someone else. And there are those who collect a whole houseful of leaves, yet until death never discover a single sweet potato. They have not even reached intellectual understanding.