Everything has Energy. Quantum physics shows that at its most basic, all matter is made up of vibrating strings of electricity. So is your body and so are crystals. Humans are better gauges of energy than you may think. Even people who aren't into crystals or energy healing may feel that they don't "vibe" with someone or something. When you experience this, you are sensing Energy and recognizing that someone else's energy isn't compatible with your own energetic vibration.