A phrase like ‘As above, so below’ is used by writers and astrologers alike to explain why and how the world works. It seems a great concept that the visible stars in the sky are linked to life on earth. The microcosm and the macrocosm are connected. On the internet using Google I find 108 million hits for ‘As above, so below’. Together with astrology I get 858.000 hits. This interests me and I am curious. Who used these words and where do they come from?
Who is Hermes Trismegistus?
Hermes Trismegistus is good for almost 35.000 hits and seems a perfect name to investigate. But that is easier said than done. There are few sources that really tell about him or his origins. It is not sure who he really was and where he lived, much speculation also.The name of Hermes Trismegistus (Greek for ‘Hermes the thrice-greatest’) is a blending of the Greek god Hermes and the Egyptian Thoth.
In Hellenistic Egypt, the name of the god Hermes was given as a substitute for the Greek name of Thoth. He was the Egyptian god of the moon and of wisdom and learning, usually represented as having the head and neck of an ibis. In the Greek mythology Hermes was the messenger of the Gods. Both these gods were associated with writing and magic and after time they became more and more the same and took each others symbolism as well.
In the Greek papyri an Egyptian Hermes Trismegistus is found. He is ‘a cosmic deity with whom the magician (in Egyptian style – cf. the ritual assumption of god-forms) could identify. In the Corpus Hermeticum Trismegistus is usually envisaged as a sage who lived in a remote period, conversing with the deities, though they also speak of him as a divine being … Apparently, Hermes Trismegistus was conceived as hovering between the divine and human world, which, being a mediator, was an advantage’.
Many hits on the internet connect Hermes Trismegistus with occult sciences, such as alchemy and astrology. This association partly originates in the technical hermetic literature circulating in the Roman empire from as early as the second century. The expression “hermetically sealed” derives from the name Hermes. Appollonius of Tyana, the Pythagorian philosopher of the first century C.E. is less well known. Greek and Latin sources do not connect these two figures doctrinally, but in the Arabic Hermetic literature [...] Apollonius (in Arabic: Balinus) is often associated with Hermes. There he is depicted as the discoverer and representative of Hermes’ teachings on the secrets of creation that had been lost to the generations before him. Apollonius has even been identified as Hermes himself.
Hermetica or hermetic books are ‘ancient metaphysical works dealing essentially with the idea of the complete community of all beings and objects. Authorship of the books was attributed to the Egyptian god of wisdom, Thoth, whose name was sometimes translated into Greek as Hermes Trismegistus and was therefore equated with the Greek god Hermes. The books treat of a variety of subjects, including magic, astrology, and alchemy, and were particularly influential in the 3rd century with the Neoplatonists and in France and England in the 17th century.’ 
The Hermetic writings can be divided into two main sections: writings on sciences, especially those of occult significance, and writings on philosophy, presenting the Hermetic doctrine and view of the world. In the scientific section a broad range of topics is covered: astrology, astronomy, alchemy, magic, geography, topography, education, worship, laws, priestly conduct, anatomy, disease, organs of the body, medicine, ophthalmology, and even gynaecology. The philosophical section is most interesting when studying Hermeticism.  In 1911 a text called Kybalion appeared. It is written by ‘three initiates’ and is called the essence of the teachings of Hermes Trismegistus. It explains the 6 principles in the universe. 
Beside the wide range of Hermetic writings there are also hits on the Tabula Smargadina or Emerald Tablet. Sources as early as 500 AD report on this tablet and what it says. Legend has it that the tabula was found in a cave by Apollonius in Egypt (near Alexandria ?) in the first century AD, inscribed on a plate of emerald, held by the corpse of Hermes Trismegistus.
In other legends (told by Albertus Magnus), Alexander the Great found it (in the third century BC).
This green tablet, sometimes called the tablet of Hermes, could even be one of the earliest works in alchemy in the world. I don’t think it is still around, but apparently on the tablet there were thirteen lines. The second line holds the ‘As above so below’-axioma that everyone refers to. [8,9]
The words “As above so below”
Quoted here is the version by Isaac Newton from circa 1680.
1. Tis true without lying, certain & most true.
2. That which is below is like that which is above & that which is above is like that which is below to do the miracles of one only thing.
3. And as all things have been & arose from one by the meditation of one: so all things have their birth from this one thing by adaptation.
4. The Sun is its father, the moon its mother,
5. The wind hath carried it in its belly, the earth its nurse.
6. The father of all perfection in the whole world is here.
7. Its force or power is entire if it be converted into earth.
7a. Separate thou the earth from the fire, the subtle from the gross sweetly with great industry.
8. It ascends from the earth to the heaven & again it descends to the earth and receives the force of things superior & inferior.
9. By this means you shall have the glory of the whole world & thereby all obscurity shall fly from you.
10. Its force is above all force, for it vanquishes every subtle thing & penetrates every solid thing.
11a. So was the world created.
12. From this are & do come admirable adaptations where of the means (or process) is here in this.
13. Hence I am called Hermes Trismegist, having the three parts of the philosophy of the whole world.
14. That which I have said of the operation of the Sun is accomplished & ended.
Sources and links:
 Explanation on the origins of Hermes Trismegistus was found on http://www.answers.com/topic/hermes-trismegistus#after_ad1
 In Tabula Smaragdina, the Emerald Table by Wim van Dungen, 2002-2006 is spoken about the legend & history of Hermes Trismegistus. This can be found at http://www.sofiatopia.org/equiaeon/emerald.htm#1a
 Hermes Trismegistus and Apollonius of Tyana in the writings of Baha’u’llah by Kevin Brown. http://www.mountainman.com.au/Hermes_Apollonius_Keven_Brown.htm%5D
 Hermes Trismegistus, the Archaic underground Tradition with quotes from the Ancient Egypt tradition and Greek accounts, as found in modern books and texts. http://www.mystae.com/restricted/streams/scripts/hermes.html
 A definition of hermetica or hermetic books can be found at http://www.encyclopedia.com/doc/1E1-Hermetic.html
 Explanation on the hermetic writings by http://students.roanoke.edu/groups/relg211/bennett/writings.html%5D
 Kybalion can be downloaded from http://www.gutenberg.com.