When you inquire 'Who am I?' if you are honest, you'll notice that it takes you right back to silence instantly. The brain doesn't have an answer, so all of a sudden there is silence.
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.