Silently. In some situations it is impossible to vibrate words out loud. In these instances you can say them to yourself, thus using the “Great Voice.” However, they should still cause the universe to vibrate (see Vibratory Formula).
Readers, please enjoy this guest blog post by Sandra Kynes, author of several books, including The Herb Gardener's Essential Guide, Plant Magic, and the new Witches' Encyclopedia of Magical Plants, among many others.
Although a few old books...