book 1-10

In a dharma talk, Dogen said,

Even if you are speaking rationally and another person says something unreasonable, it is wrong to defeat him by arguing logically. On the other hand, it is not good to give up hastily saying that you are wrong, even though you think that your opinion is reasonable.

Neither defeat him, nor withdraw saying you are wrong. It is best to just leave the matter alone and stop arguing. If you act as if you have not heard and forget about the matter, he will forget too and will not get angry. This is a very important thing to bear in mind.

Book 1-11

Impermanence is swift; life-and-death is a vital matter. For the short while you are alive, if you wish to study or practice some activity, just practice the Buddha-Way and study the buddha-dharma. Since literature and poetry are useless, you should give them up. Even when you study the buddha-dharma and practice the Buddha-Way, do not study extensively. Needless to say, refrain from learning the Exoteric and Esoteric scriptures of the teaching-schools. Do not be fond of learning on a large scale, even the sayings of the buddhas and patriarchs. It is difficult for us untalented and inferior people to concentrate on and complete even one thing. It is no good at all to do many things at the same time and lose steadiness of mind.
I would like to thank all things for bringing this text into being, which is really nothing, yet is of great use for practice.