Grounding and Centering
Grounding has two aspects to it:
When beginning a working, it is tapping into the Earth and drawing up sufficient energy to complete whatever working you are doing. In a circle, the "tap" is kept open until the working is complete, and it will power the working without draining the Priest of her personal energy.
At the end of the working, grounding is letting that "tap" go and giving all the excess energy back to the Earth. Visualization, physically touching the Earth, or shaking the energy off are all ways to get rid of the excess energy.
Centering can be done in several ways, but the main idea is to visualize the movement of energy in your body in a stable and usable form. This is so that you can control where the energy goes when you pull it out of yourself to use it. There are many ways this can be done, and we recommend finding a way that works best for you. We typically teach the Willow Tree meditation and Middle Pillar, but these are by no means the only ways.
The Importance of Grounding and Centering
Many witches (ourselves included) can forget the physical toll that working magick can take on one's body. If you were to use only your own energy to power a working, you would be completely exhausted by then end of it. Or, if you raise a lot of energy for a working, you could be so "high" from the energy that you may not be able to sleep (for several days, even). Grounding and Centering mitigates these effects. When properly grounded with the energy centered, you will not drain yourself of your own energy during the working. Properly grounding the energy after the working will help bring you back into this reality, and allow you to sleep afterwords. We also call this the "prevention of Magickal Hangovers", which can feel just like the mundane version of a hangover. We also recommend eating protein-rich foods and drinking lots of water after a working, as we have found that this also helps with grounding and re-hydrating (especially after the more energetic circles).
In some Pagan corners, grounding after a ritual is not done because it is seen as giving your power away. This, to us, is a misunderstanding of what grounding actually is, and possibly the mix up of the ideas of Magickal Power (what is used and raised in circle) and Power-Over (a concept of the use of societal, social, and political Power in the mundane world). Grounding in a magickal working is not giving away your personal power, but taking Power from the Earth, and then returning any excess. Giving up one's personal power to another, or using all of your own personal power in a working, are both pretty bad ideas, and we don't recommend either.
The Willow Tree Meditation
Imagine that you have a tap root, as a willow does, and sink it down into the Earth. Down, down, into the very heart of the Earth. Feel the energy there and stick your tap root into it. Allow the energy to flow upwards and also pull it up into your feet. Let it pool there and move deosil, swirling around your feet until it glows bright. Then, bring it up to your knees and let it build there. When it, too, is bright then bring to your hips and let it swirl deosil from your feet to your hips. Then bring it up to your heart, and let it flow into your arms and hands. Then, when the power is flowing through your body, bring it into your head. Let the power build in your body and head until you are glowing bright white and that you can barely contain it. Then, let it shoot out of the top of your head like the branches of a willow tree that are long and eventually touch the ground. When they touch the ground, let the power flow from your feet, up your body, out your head and back into the ground again. Let your branches mingle with the branches of the ones next to you, and feel the power moving deosil in the circle.
(Allow a minute or so for people to feel the flow of power. Starting a chant at this time also works well.)