If we throw a piece of stone in a tank or a pool of water, it will produce a succession of concentric waves travelling all around from the affected place.
The light of a candle will similarly give rise to waves of ethereal vibrations travelling in all directions from the candle.
In the same manner, when a thought, whether good or evil, crosses the mind of a person, it gives rise to vibrations in the Manas or mental atmosphere, which travel far and wide in all directions.
What is the possible medium through which thoughts can travel from one mind to another? The best possible explanation is that Manas or mind-substance fills all space like ether and it serves as the vehicle for thoughts, as Prana is the vehicle for feeling, as ether is the vehicle for heat, light and electricity and as air is the vehicle for sound.
– Swami Sivananda