One day Dogen instructed,

An ancient has said, “Associating with a good person is like walking through mist and dew; though you will not become drenched, gradually your robes will become damp.” This means that if you become familiar with a good person, you will become good yourself without being aware of it.

In ancient times a boy who attended Master Gutei (Judi), without noticing when he was learning or when he was practicing, realized the Way because he had served as a personal attendant to the master who had been practicing for a long time.

Similarly if you practice zazen for a long time you will suddenly clarify the Great Matter and will know that zazen is the true gate to the buddha-dharma (Shobogenzo Zuimonki, Book 4, Chapter 4).