As with everything in nature, our physical body has a double, known as the etheric double, which penetrates it and extends beyond it

"As with everything in nature, our physical body has a double, known as the etheric double, which penetrates it and extends beyond it. This means that each limb of our body has its double. Our arm, for example, is penetrated by an etheric double which extends beyond the contours of our fingers. And if a musician, a violinist, for example, has learned by way of his imagination to introduce his etheric arm into his instrument so that it impregnates the wood and the strings, the instrument vibrates differently. A musician can produce sounds beyond the physical sounds, which sensitive people are able to perceive.
The same law exists for the voice: when certain artists sing or speak, they change the vibrations not only in the hall but in the physical bodies of the audience, because of the work they have done consciously or unconsciously on their etheric body. And with everything we emanate through our etheric body, we too can animate places and creatures."