Correspondence with Sri Aurobindo
II. Personal Relations in the Spiritual Life
What exactly is vital interchange?
Difficult to specify. There is always a drawing of vital forces from one to another in all human social mixture that takes place automatically. Love-making is one of the most powerful ways of each drawing upon the other's vital force, or of one drawing the other's, which also often happens in a one-sided way to the great detriment of the “other”. In the passage come many things good and bad, elation, feeling of strength and support, infiltration of good or bad qualities, interchange of psychological moods, states and movements, depressions, exhaustion – the whole gamut. People don't know it – which is a mercy of God upon them – but when one gets into a certain Yogic consciousness, one becomes very much aware and sensitive to all this interchange and action and reaction, but also one can build a wall against, reject etc. etc.
It is a wall of consciousness that one has to build. Consciousness is not something abstract, it is like existence itself or ananda or mind or prana, something very concrete. If one becomes aware of the inner consciousness, one can do all sorts of things with it, send it out as a stream of force, erect a circle or wall of consciousness around oneself, direct an idea so that it shall enter somebody's head in America etc. etc.
I don't understand why you call it God's mercy?
Because ignorance is bliss and they would feel very uncomfortable if they felt these things or were at all aware of them. As for the elation, they get it without needing to know the cause.