INVOCATION/EVOCATIO N
There are so many people who say they invoke the Goddess or they invoke the elements. The question is--do they invoke or do they evoke? Invocation and evocation are two separate things..
INVOCATION:
Invocation is when you want that particular entity to step into your body, and you become them, and you absorb those particular energies. In many covens, different pagans will call in a particular quarter, and, when they do, they become that quarter, absorbing that particular energy so much so that they become that Quarter. They then have to stand at that Quarter and guard it, as they are the actual Guardian of that direction. It is interesting but several covens have "words of wisdom" wherein say a pagan, who has invoked a particular Quarter then speaks of wisdom of that element, as the Element is actually speaking through them. The same would be if you invoke the Goddess.
When one draws down the Moon, they are invoking the Goddess into them, and then they are the Goddess. Many of your Wiccan covens say only a male can invoke the Goddess into a female. This is not true. This is solely an idea of Gerald Gardner for male to not only participate in coven rituals but to have some control, when in all actuality, you need no one but yourself to call Her into you. Long ago, when a Witch stood out alone under the bright shining Moon, it was she, the Witch, who called the Moon into herself. Her and her alone.
When people do channeling and an entity takes over the channel or's body, they are invoking that entity into them.
A word of warning. You do not want to invoke all the Quarters into you during ritual if you are the only person in that circle. Nor do you wish to invoke a Quarter plus the Goddess. Only one entity should be in you at one ritual.
EVOCATION:
Evocation is when you invite the Goddess or element to circle but to be with you in circle and not within you. This is generally done when you are a solitaire, and you invite the Quarters to attend and guard your circle and that is all. When you are at the altar and you ask the Goddess to be with you that night and light Her candle, you are evoking Her. You are asking Her to join you for that rite. You can then later invoke Her into you, if you wish. However, a lot of witches do not draw the moon down into themselves each and every time they have ritual. A lot of people who claim they speak with departed ones "evoke" that person¢s spirit, because they certainly do not want them within them.
Depending on your frame of mind, you invoke or evoke but know what you want to do before you start your circle. Always be prepared anytime you are to do ritual work. Most people do both as far as the Goddess is concerned but only evoke the elements. You would be one charged up "puppy" if you brought them all into you and plus you are just asking for trouble if you did that.