If you desire to be pure, have firm faith, and slowly go on with your devotional practices without wasting your energy in useless scriptural discussions and arguments. Your little brain will otherwise be muddled.
Anything that is secret and mysterious in this system of Yoga should be at once rejected. The best guide in life is strength. In spirituality, as in all other matters, discard everything that weakens you. Have nothing to do with it. Mystery-mongering weakens the human brain. It has well-nigh destroyed Yoga, one of the grandest of sciences
Science, already oppressive with its shocking revelations, will perhaps be the ultimate exterminator of our human species - if separate species we be - for its reserve of unguessed horrors could never be borne by mortal brains if loossed upon the world.
There are three kinds of brains. The one understands things unassisted, the other understands things when shown by others, the third understands neither alone nor with the explanations of others.
In order to explain why the ordinary Sadhus and Yogis take to tobacco and gānja [an intoxicant], I said that these cause stimulation of the physical brain. But these have reactions. And to stimulate the brain thus is not the proper process.
My fundamental premise about the brain is that its workings - what we sometimes call "mind" - are a consequence of its anatomy and physiology, and nothing more.