= Why =
You must be pure for the love of purity.
The world will be made better only in proportion as we make ourselves better. The ills that humanity suffers from - collectively and individually - stem from the errors that lie at the roots of our ignorant nature. Thus, purification of our nature is central to making the world better.
We are the deforming intermediary between the purity of the animal and divine purity of the gods. Thus, the process of purification is central to our evolution.
importance of purity also comes through when one sees how with inner liberation, total sincerity and perfect purity, all sufferings ends because they will no longer be required for the progress of consciousness.
'''Purification in Yoga'''
From a yogic perspective, purification is of utmost importance. All yoga proceeds in its methods by three principles of practice - purification, concentration and consummation. The importance of purification also emerges from the Gita and Patanjali’s Yoga-sutras. The Gita sees the darkness of ignorance is the cause of all stumblings and purification through Self-knowledge as the most sovereign purity. Patanjali’s Yoga-sutras insists first on a moral purification of the mentality - divided into yamas (self-discipline by which rajasic egoism and it's passion and desires are conquered and quieted) and niyamas (discipline of the mind by regular practice of meditation).
= How =