Vibration
Everything vibrates. The higher the vibration, the less dense the object. Spirit vibrates at a higher level to us - so in order to communicate with spirit, they need to lower their vibration as we raise ours to meet somewhere in the middle. A good example of how vibration works in this respect is a bee flying. You can see the bee, but you cannot see it's wings. This is because the wings are vibrating at a high rate to keep the bee aloft and this high rate of vibration cannot be perceived with the human eye. The higher we raise our consciousness (our vibration), the wiser and more pure the spirit communicator.
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