‘Any Energy you send out will come back three-fold’
Basically, this is the natural law of “cause and effect”. The Goddess charges us to exercise great care in all that we, as Witches, do and say and even think.
The Threefold Law takes the notion that “what we reap, we will sow”, a few steps further, in fact, THREE steps further.
For what we do “for good or for ill, shall be returned to us threefold.” In light of this fact, Witches are loath to cause any harm, lest it be returned to them in spades!!