The Pentagram is an ancient symbol meaning that the Spiritual rules over the other 4 bodies – the physical body, the emotional body, the intellectual body and the passion body – all those bodies come under the Spiritual control. Know Thyself is the answer to that question – to be able to contain the erratic and often opposing forces of those other 4 bodies under the spiritual takes an act of Will. You understand that the Will is Spiritual – it is the cause and what appears in the physical. To align oneself with Spiritual Principles – like Natural Law – keeps one out of the fray or unprincipled action – nihilism – we see perpetrated upon us by the media and tell-lie-vision.
Understanding all this, the reverse pentagram is simply when the Spiritual Head is driven into the earth and the 4 bodies rule through base desire.