Mental
Purification
induces pure Happiness!

The purpose of purification of Morality is
the purification of Mentality!
The purpose of purification of Mind is the
purification of Understanding!
The purpose of purification of Understanding is
the overcoming of Doubt!
The purpose of overcoming Doubt is
knowing what to do,
and what not to do!
The purpose of knowing what to do,
and not do, is purification of the Method!
The purpose of purification of the Method is
purity of Knowledge and Vision!
The purpose of purification of Knowledge
and Vision is Release from all clinging!
The purpose of Relinquishing all clinging is
the only Supreme Bliss:
Nibbāna...

More on Purification
(Visuddhi):
Mental_Purity,
Levels of Leaving Behind,
The_7_Purifications,
The_7_stages_of_Purification,
Ability_Purification,
The_8_Understandings,
Immaculate_Integrity.

Source:
The Middle Length Sayings of the Buddha.
Majjhima Nikāya.
Sutta 24 Relays.
http://store.pariyatti.org/Middle-Length-Discourses-of-the-Buddha_p_1543.html
https://What-Buddha-Said.net/library/ati_website/html/tipitaka/mn/index.html
