In the Soto school of Zen, meditation with no objects, anchors, or
content, is the primary form of practice. The meditator strives to be
aware of the stream of thoughts, allowing them to arise and pass away
without interference. Considerable textual, philosophical, and
phenomenological justification of this practice can be found throughout
Dōgen's
Shōbōgenzō, as for example in the "Principles of Zazen"
[web 14] and the "Universally Recommended Instructions for Zazen".