You do not have to be an occultist in order to see the wisdom in the Seven Hermetic Principles, you do not have to dive into the realms of obscure mysticism or spend the rest of your life studying any ancient secrets to understand them. Nor is it necessary to know one Hermes Trismegistus, whether he might be a variation of an ancient god - Hermes, Thoth, Enoch, whoever - or merely a kind of medieval superman of the occult revived in the Victorian fascination for pompous myths.
On the contrary, it's always healthier to have a good grain of salt at hand when the 'initiated' authors get a tad to melodramatical.. ;) Nevertheless, the Seven Hermetic Principles contain a good glance at the thought of ancient philosophy, thus embodying an universal truth, independent from any belief, based merely on the nature of 'things' - such as the world, the life, the being, the ALL. They neither contradict philosophy or phsics, and when you think of it, not even copmmon sense.
The Seven Hermetic Principles, as simple and few as they seem, are a set of axioms whose understanding will ultimately refine your view on life and being - doubtlessly an inalienable basic to get behind the depht of Tarot.
Below you find a short list of the Seven Hermetic Principles:
1. The Principle of Mentalism The All is mind; the Universe is mental
2. The Principle of Correspondence As above, so below; as below, so above
3. The Principle of Vibration Nothing rests; everything moves; everything vibrates
4. The Principle of Polarity Everything is Dual; everything has poles; everything has its pair of opposites; like and unlike are the same; opposites are identical in nature, but different in degree; extremes meet; all truths are but half-truths; all paradoxes may be reconciled
5. The Principle of Rhythm Everything flows, out and in; everything has its tides; all things rise and fall; the pendulum-swing manifests in everything; the measure of the swing to the right is the measure of the swing to the left; rhythm compensates
6. The Principle of Cause and Effect Every Cause has its Effect; every Effect has its Cause; everything happens according to Law; Chance is but a name for Law not recognized; there are many planes of causation, but nothing escapes the Law
7. The Principle of Gender Gender is in everything; everything has its Masculine and Feminine Principles; Gender manifests on all planes (Raven's Tarot Site)