Sounds are really energy manifest. The sound is not merely an empty form of verbal manifestation, but enemy that is made to express itself in a particular shape. And when this packet of enemy, this tied up form of force, which is a particular letter of the alphabet, is made to come in contact with another packet of energy called another letter, they collide with each other act upon each other or fuse into each other, so that the utterance of a group of letters, which is the Mantra, produces, by the process of permutation and combination of these letters, a new form of energy which gets infused into our system. Because it has arisen from our own mind, thought and the recesses of our being, we get charged with that force, as if we have touched a live electric wire. There is special name given to this science, as Gana Shastra, in Tantrik parlance.
Words are forces, thoughts are things.
They are not empty sounds. It is because of the fact that thoughts and expressions are powers by themselves, that the words of saints lake immediate effect. The words that a saint or a sage utters are not empty sounds that he makes. They are forces that are released like atom bombs, and they can manifest themselves in the physical world, and events can take place. That is why people go to a Mahatma for Asirvada, or blessings.