Visuddhimagga

The Visuddhimagga ("The path to purity") is a Theravāda Buddhist commentary written by Venerable Buddhaghosa approximately in 430 CE in Sri Lanka. It is considered the most important Theravāda text outside of the Tipiṭaka canon of scriptures.

The Visuddhimagga's structure is based on the Ratha-vinita Sutta ("Relay Chariots Discourse," MN 24), which describes the progression from the purity of discipline to the Nibbāna, considering seven steps.

This comparison between practice and "seven relay chariots" points at the goal. Each purity is needed to attain the next.

(1) Purity in terms of virtue
(2) Purity in terms of mind (that is, concentration)
(3) Purity in terms of view
(4) Purity in terms of the overcoming of perplexity
(5) Purity in terms of knowledge and vision of what is and what is not the path
(6) Purity in terms of knowledge and vision of the way
(7) Purity in terms of knowledge and vision