Zen is a school of Mahayana Buddhism that originated in China during the Tang dynasty as Chán. It was strongly influenced by Taoism, and developed as a distinguished Chinese style of Buddhism. Zen emphasizes rigorous meditation-practice, insight into Buddha-nature, and the personal expression of this insight in daily life, especially for the benefit of others. As such, it de-emphasizes mere knowledge of sutras and doctrine and favours direct understanding through zazen(meditation) and interaction with an accomplished teacher.
Rinzai is the Japanese line of the Chinese Linji school, which was founded during the Tang Dynasty by Linji Yixuan.The Rinzai-tradition emphasizes kensho, insight into one’s true nature. This is followed by so-called post-satori practice, further practice to attain Buddhahood. Other Zen-teachers have also expressed sudden insight followed by gradual cultivation. To attain this primary insight and to deepen it, zazen and kōan-study is deemed essential. This trajectory of initial insight followed by a gradual deepening and ripening is expressed by Linji in his Three mysterious Gates, and the Four Ways of Knowing of Hakuin. Another example of depiction of stages on the path are the Ten Ox-Herding Pictures which detail the steps on the Path.
Sōtō is the Japanese line of the Chinese Caodong school, which was founded during the Tang Dynasty by Dongshan Liangjie. The Sōtō-school has de-emphasized kōans since Gentō Sokuchū (circa 1800), and instead emphasized shikantaza. Dogen, the founder of Soto in Japan, emphasised that practice and awakening cannot be separated. By practicing shikantaza, attainment and Buddhahood are already being expressed. For Dogen, zazen, or shikantaza, is the essence of Buddhist practice. Gradual cultivation is also recognized by the Caodong-teacher Tozan. The first syllable of his name is part of the word “Soto”.
The Sanbo Kyodan combines Soto and Rinzai teachings. It is a Japanese lay organization, which is highly influential in the West through the work of Hakuun Yasutani, Philip Kapleau, Yamada Koun, and Taizan Maezumi. Yasutani mentions three goals of Zen: development of concentration (joriki), awakening (kensho-godo), and realization of Zen in daily life (mujodo no taigen). Kensho is stressed, but also post-satori practice.