If you desire to wash off the dirt accumulated from the clothes you wear, you need both soap and clean water. So too, if you are anxious to remove the impurities that have got accumulated in the mind, both Vidya (spiritual knowledge) and Thapas (penance) are essential. Only when both are used can the levels of consciousness be thoroughly cleansed. No vehicle can move without at least two wheels, nor can a bird fly with just one wing. So too, no one can be rendered holy or purified without Vidya and Thapas.

Vidya Vahini, Chap XII.