However, it is not necessary for a healer to see auras at all in order to do energy work. Everyone has his or her own way of perceiving subtle energy, and one way is not better than another. For example, many healers sense the energy field with their hands. I've heard of energy healers who do good work without sensing energy at all.
Nonetheless, it can be interesting and useful for a healer to see the biofield. Here's a site that gives detailed instructions for developing this ability: www.thiaoouba.com/seeau.htm.
Here's a page if you're interested in exploring aura color meaning. There are other ways to discern your own aura colors besides seeing them, and this page gives you one that's both fun and accurate.
You can learn two exercises for developing hand sensitivity to subtle energy here.It's quite exciting when you first learn to feel the energy. (And continues to be exciting, even after many years, from my experience.)
And you can learn about sensing chakras, another part of the energy system, here.
Learn more about energy healing, including practical tips to keep yourself and your family healthier and happier. You'll receive my "Seven Chakras at at Glance" chart as a gift.
Do-It-Yourself Energy Healing for a More Joyful, Loving, Fruitful Life
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Learn more about energy healing, including practical tips to keep yourself and your family healthier and happier. You'll receive two gifts: my "Seven Chakras at at Glance" chart and "First Chakra: Get Beyond Anxiety To A Sense Of Peace And Security."