Modern biology says that the human brain was meant by Nature to guide the organic (physical and nervous) system, not vice versa as it is with millions of people. B. G. Walter, in his book, The Living Brain, says: “When we were students in Cambridge under Sir Joseph Barcroft, he gave us a dictum coined by a famous French physiologist: a fixed interior milieu is a condition for a free life.”
Early mammals had no thermostatic equilibrium and their nervous system could not function quickly. Nature tackled this by building the thermostatic apparatus in later mammals so that whatever the temperature outside, the temperature within was constant. This is called fixed interior milieu.
At the human level, this perfection is called the homeostasis condition: our bodies have an automatic system of stabilising the inner man, which allowed the evolution of the higher brain. The higher brain is not for mere survival. It is “for taking man to freedom”. For other animals, homeostatis is meant only for survival: for man it is a means for emancipation.
Through our wonderful apparatus, the cerebral system, we can discipline our energies and bring calmness within, create our fixed interior milieu. This level is what we call yoga, samadhi or nirvana. The Katha Upanishad defines yoga as: Yada pancha vatishthante jnanani manasa saha/buddhischa na vicjeshtati tamahuh paramam gatim tam yogamiti manyante.
“When the five sense organs are made calm, when the mind also does not flicker, even the seasoned intellect becomes absolutely steady: that is the highest state of existence.”
This experience is what the Buddha achieved as Nirvana. Man becomes free through the scientific pursuit of yoga without any ‘magic’ of religion. We discover our own infinite nature. Abridged from Man the Known & Man the Unknown, Sri Ramakrishna Math.