Everything has an ideal vibration where that state brings it into harmony with its surroundings. When something vibrates disharmoniously problems are likely to follow. When we resonate with something it means it appeals to us because there is harmony in what we see, hear, feel, and so on. Compare the painful screeching of brakes to the delight of a song. Compare the appeal of a fine painting to the unappealing stain of leftover paints congealing in the bottom of a paint tin.
When our energy centres are vibrating at the optimum level we feel happy and contented and healthy. When our energy centres are vibrating at incorrect frequencies, we feel unhappy and discontented and unhealthy. Fortunately, there are standard blueprints of harmonious vibrations which we can draw upon to help our energy centres resonate happily. Colour, sound and crystals are just some of those standard vibrational forms which can help us achieve a higher standard of health.