Astrology is a very broad term for a whole range of beliefs based on watching the heavens; in particular stars and constellations, planets, comets (and other more temporary phenomena) and the moon in the night sky. In a basic sense it’s “star divination”. Think of the of the Hermetic “As above, so below” or “As in the macrocosm, so in the microcosm”. That which is written in the stars has an influence of what is below. The better you understand the heavens the better you can understand what is written in one’s fate. Better and better measurements of the heavens broke up the old paradigms and created genuine Astronomy. For centuries the line between astrology and astronomy was blurred. It is impossible to look at the history of astronomy without understanding that motivation between more accurate start charts and mathematical models was astrology, in particular horoscopes. To get a better grasp of astrology before we talk about how it connects to alchemy, we did a show on its roots in Sumeria and Mesopotamia, and the Babylonian influence on Greek Astrology:

Astrology ties in heavily with Alchemy and other Mysticism such as Neoplatonism and Hermeticism Tie to alchemy: Gold – Sun Silver – Moon Tin – Jupiter Mercury – Mercury Copper – Venus Iron – Mars Lead – Saturn All zodiac signs have coldmoistdry, and hot, influences, as do planets. – Llull’s Theory Pico della Mirandola was against Astrology in the sense of horoscopes and determinism, but still believed in the above. (As does Renaissance Neoplatinism.) Al-Ghazali believed that God’s will was disturbed or corrupted by the heavenly bodies as it made its way from Heaven to Earth. So to counteract this corruption one needed to understand it. See: the podcast page for details, since almost ever episode of alchemy is tied to astrology in some way. Theory of the Elements is not Astrological, but is based on the stars (Yates calls it astral science)

  1. Sumerian and Babylonian Astronomy & Astrology
  2.  Sumerians
  3.  Astrolatry
  4.  Periodicity:
  5.  Planetary theory
  6. Cosmology
  7. Astrology:
  8. Heliocentric astronomy
  9. Babylonian influence on Hellenistic astronomy
  10. Early influence
  11. Influence on Hipparchus and Ptolemy
  12. Means of transmission
  13. Astrology as Divination
  14. Planets and gods
  15. System of Interpretation

Sumerian and Babylonian Astronomy & Astrology

To go back to the very beginning of Alchemy, and to split Sumerian and Babylonian Astronomy away from Astronomy and Astrology in general, we wanted to give Mesopotamian Alchemy and Astrology its own show. There’s definitely enough interesting stuff to talk about and we thought our Astrology episode would get too long if had to give a history of some 4 thousand (or more) years of Astrology in one show.

When we talk about astronomy, or even about science more generally, and even influences on alchemy, we are talking about a continuing tradition that started in Mesopotamia and has a direct, unbroken line to present day.

Let’s start by reaching back as far as we can: Sumerians.

Our knowledge of Sumerian astronomy is indirect, via the earliest Babylonian star catalogues dating from about 1200 BCE. But many of the star names are in Sumerian, which could take astronomy back to the early Bronze Age, or the 3rd Millenium BC.

Now, in our introduction and the episode on Hermes, we’ve discussed that t we here at the History of Alchemy Podcast consider the 4th Century Alexandria to be just about the beginning of what we would consider Alchemy. Maybe as far back as the 1st Century based on Zosimos’ writings, but that’s pushing it.

So why are we going back another 2 thousand years before that? Two reasons:

  • To look at the very beginning of observational science.

  • And as we’ve said many times before, you can’t have late antiquity and medieval alchemy without astrology.

We’ll do a much better job of tying astrology into alchemy in a later episode, but for now, let’s get a good handle on the beginnings of astrology, astronomy and Astrolatry, so that later episode has something to build on… plus. This stuff is really interesting for a history nerd like myself.


A couple things we need to define:


Sumerians who developed the earliest writing system—known as cuneiform—around 3500–3200 BC. The Sumerians developed a form of astronomy that had an important influence on the sophisticated astronomy of the Babylonians.

 The Sumerian city of Eridu, on the coast of thePersian Gulf, was the world’s first city,

They’re intesting because it’s a laguage isolate.

Sumer, the city where we get the name from, were first settled ca. 4500 and 4000 BC by a non-semitic people. As opposed to Akkadians, who were semitic, and over a long time where both Sumerian and Akkadian was written and spoken, the Akkadian language slowly dominated until Sumerian disappeared.

 They also used a sexagesimal(base 60) place-value number system, which simplified the task of recording very great and very small numbers. The modern practice of dividing a circle into 360 degrees, of 60 minutes each hour, began with the Sumerians.


Astrolatry, which gave planetary gods an important role in Mesopotamian mythology and religion, began with the Sumerians.

 Think of what the planets are called: names of Gods. This started with Sumerians, and was taken over by Babylonians, and from there to Greeks and Romans.

Astrolatry was banned in the Bible in Deuteronomy,  for the interested.

 From here, we mention Babylonians a lot.. we’re simplifying. we could be talking about  the Akkadian Empire, Gutian, Ur III, neo-Babylonians, even Chaldean, Achaemenid, Seleucid, and Parthian.. etc. It’s probably more accurate to say Mesopotamians. but we’re not going to. There are other podcasts that deal with the history of the ancient world, and break it down. And those are worth a listen, but we’re focused on the science that these people brought to the Greeks more they dynasties of Mesopotamia. But when Greko-Babylonian Astrology is said (and it’s not just us that is guilty of that) that is a very big over-simplification.

So anyway.. The babylonians inherited these beginnings from the Sumerians and built on it:

When we talk about greeks trying to make a logical sense of the universe, this is something we can see the Babylonians doing before them:

During the 8th and 7th centuries BCE, Babylonian astronomers developed a new empirical approach to astronomy. We get star charts and predictions.

They began studying philosophy dealing with the ideal nature of the universe and began employing an internal logic within their predictive planetary systems.

This approach can’t be understated. It’s maybe the first scientific revolution. And certainly contributed to astronomy and the philosophy of science.

When you hear ‘Chaldeans,’ which was a short lived dynasty in Babylon, normally we think of a Greek or Latin source speaking of astronomers of Mesopotamia.

Chaldeans were really specializing in astrology and other types of divination.

according to the historian A. Aaboe, Babylonian astronomy was “the first and highly successful attempt at giving a refined mathematical description of astronomical phenomena” and that “all subsequent varieties of scientific astronomy, in the Hellenistic world, in India, in Islam, and in the West—if not indeed all subsequent endeavour in the exact sciences—depend upon Babylonian astronomy in decisive and fundamental ways.”


The Babylonians were the first to recognize that astronomical phenomena are periodic and apply mathematics to their predictions. Tablets dating back to the Old Babylonian period document the application of mathematics to the variation in the length of daylight over a solar year. Centuries of Babylonian observations of celestial phenomena are recorded in the series of cuneiform tablets known as the Enûma Anu Enlil—the oldest significant astronomical text that we possess is Tablet 63 of the Enûma Anu Enlil, the Venus tablet of Ammisaduqa, which lists the first and last visible risings of Venus over a period of about 21 years. It is the earliest evidence that planetary phenomena were recognized as periodic.

 The MUL.APIN contains catalogues of stars and constellations as well as schemes for predicting heliacal risings and settings of the planets, and lengths of daylight as measured by a water clock, gnomon, shadows, and intercalations. The Babylonian GU text arranges stars in ‘strings’ that lie along declination circles and thus measure right-ascensions or time intervals, and also employs the stars of the zenith, which are also separated by given right-ascensional differences. There are dozens of cuneiform Mesopotamian texts with real observations of eclipses, mainly from Babylonia.

 Planetary theory

The Babylonians were the first civilization known to possess a functional theory of the planets. The oldest surviving planetary astronomical text is the Babylonian Venus tablet of Ammisaduqa, a 7th-century BC copy of a list of observations of the motions of the planet Venus that probably dates as early as the second millennium BC.

The last stages in the development of Babylonian astronomy took place during the time of the Seleucid Empire (323–60 BC). In the 3rd century BC, astronomers began to use “goal-year texts” to predict the motions of the planets. These texts compiled records of past observations to find repeating occurrences of ominous phenomena for each planet. About the same time, or shortly afterwards, astronomers created mathematical models that allowed them to predict these phenomena directly, without consulting past records.


Take this with a grain of salt, it’s hard to piece together what they believed based on current tablets, but:

In Babylonian cosmology, the Earth and the heavens were depicted as a “spatial whole, even one of round shape” with references to “the circumference of heaven and earth” No flat earth theory here folks.

Their worldview was not exactly geocentric either. This is pre-geocentric. That idea hasn’t even come yet. How you like them apples? That was Aristotle much later.

 It’s possible they believed both the Earth and the cosmos revolved.

The Babylonians and their predecessors, the Sumerians, also believed in a plurality of heavens and earths. This idea dates back to Sumerian incantations of the 2nd millennium BC, which refers to there being seven heavens and seven earths, linked possibly chronologically to the creation by 7 generations of Gods.


The Babylonian astrologers also laid the foundations of what would eventually become Western astrology. The Enuma anu enlil, written during the Neo-Assyrian period in the 7th century BC, comprises a list of omens and their relationships with various celestial phenomena including the motions of the planets.

A significant increase in the quality and frequency of Babylonian observations appeared during the reign of Nabonassar(747–734 BC), who founded the Neo-Babylonian Empire. The systematic records of ominous phenomena in Babylonian astronomical diaries that began at this time allowed for the discovery of a repeating 18-year Saros cycle of lunar eclipses, for example.

I think it’s important to note that exact observation for the purpose of divination, led to better theories of predicting lunar eclipses.

The Egyptian astronomer Ptolemy later used Nabonassar’s reign to fix the beginning of an era, since he felt that the earliest usable observations began at this time.

We’ll break down Babylonian Astrology better at the end of the podcast.

 Arithmetical predictions

Most of the predictive Babylonian planetary models that have survived were usually strictly empirical and arithmetical, and usually did not involve geometry, cosmology, or speculative philosophy like that of the later Hellenistic models, though the Babylonian astronomers were concerned with the philosophy dealing with the ideal nature of the early universe.

In contrast to Greek astronomy which was dependent upon cosmology, Babylonian astronomy was independent from cosmology. Whereas Greek astronomers expressed “prejudice in favor of circles or spheres rotating with uniform motion”, such a preference did not exist for Babylonian astronomers, for whom uniform circular motion was never a requirement for planetary orbits.

There is no evidence that the celestial bodies moved in uniform circular motion, or along celestial spheres, in Babylonian astronomy. See our Kepler & Brahe episode, to hear how much it took for later thinkers to overcome the Helenistic view.

Contributions made by the Chaldean astronomers during this period include the discovery of eclipse cycles and saros cycles, and many accurate astronomical observations. For example, they observed that the Sun’s motion along the ecliptic was not uniform, though they were unaware of why this was; it is today known that this is due to the Earth moving in an elliptic orbit around the Sun, with the Earth moving swifter when it is nearer to the Sun atperihelion and moving slower when it is farther away at aphelion.

Chaldean astronomers known to have followed this model include

  • Naburimannu (fl. 6th–3rd century BC),
  • Kidinnu (d. 330 BC),
  • Berossus (3rd century BCE), and
  • Sudines (fl. 240 BCE).

They are known to have had a significant influence on the Greek astronomer Hipparchus and the Egyptian astronomer Ptolemy, as well as other Hellenistic astronomers.

Heliocentric astronomy

Seleucus of Seleucia (b. 190 BC), who supported Aristarchus of Samos’ heliocentric model. Seleucus, however, was unique among them in that he was the only one known to have supported the heliocentric theory of planetary motion proposed by Aristarchus, where the Earth rotated around its own axis which in turn revolved around the Sun. According to Plutarch, Seleucus even proved the heliocentric system through reasoning, though it is not known what arguments he used. Possibly tides.

According to Bartel Leendert van der Waerden, Seleucus may have proved the heliocentric theory by determining the constants of a geometric model for the heliocentric theory and by developing methods to compute planetary positions using this model. He may have used trigonometric methods that were available in his time, as he was a contemporary of Hipparchus.

None of his original writings or Greek translations have survived, though a fragment of his work has survived only in Arabic translation, which was later referred to by the Persian philosopher Muhammad ibn Zakariya al-Razi (865-925).

The Babylonians expressed all periods in synodic months, probably because they used a lunisolar calendar. Various relations with yearly phenomena led to different values for the length of the year.

Babylonian influence on Hellenistic astronomy

Until the 19th century through archeology, most of this was forgotten, and it was thought that the greeks came up with most of this themselves.

Since the rediscovery of the Babylonian civilization, it has become apparent that Hellenistic astronomy was strongly influenced by the Chaldeans. The best documented borrowings are those of Hipparchus (2nd century BCE) and Claudius Ptolemy (2nd century CE).

Early influence

Many scholars agree that the Metonic cycle is likely to have been learned by the Greeks from Babylonian scribes. Meton of Athens, a Greek astronomer of the 5th century BCE, developed a lunisolar calendar based on the fact that 19 solar years is about equal to 235 lunar months, a period relation already known to the Babylonians.

In the 4th century, Eudoxus of Cnidus wrote a book on the fixed stars. His descriptions of many constellations, especially the twelve signs of the zodiac, are suspiciously similar to Babylonian originals. The following century Aristarchus of Samos used an eclipse cycle of Babylonian origin called the Saros cycle to determine the year length. However, all these examples of early influence must be inferred and the chain of transmission is not known.

Influence on Hipparchus and Ptolemy

It is clear that Hipparchus (and Ptolemy after him) had an essentially complete list of eclipse observations covering many centuries. Most likely these had been compiled from the “diary” tablets: these are clay tablets recording all relevant observations that the Chaldeans routinely made. Preserved examples date from 652 BC to AD 130, but probably the records went back as far as the reign of the Babylonian king Nabonassar: Ptolemy starts his chronology with the first day in the Egyptian calendar of the first year of Nabonassar; i.e., 26 February 747 BC.

Similarly various relations between the periods of the planets were known. The relations that Ptolemy attributes to Hipparchus in had all already been used in predictions found on Babylonian clay tablets.

Other traces of Babylonian practice in Hipparchus’ work are

  • first Greek known to divide the circle in 360 degrees of 60 arc minutes.
  • first consistent use of the sexagesimal number system.
  • the use of the unit pechus (“cubit”) of about 2° or 2½°.
  • use of a short period of 248 days = 9 anomalistic months.

Means of transmission

All this knowledge was transferred to the Greeks probably shortly after the conquest by Alexander the Great (331 BC). According to the late classical philosopher Simplicius (early 6th century), Alexander ordered the translation of the historical astronomical records under supervision of his chronicler Callisthenes of Olynthus, who sent it to his uncle Aristotle.

Okay, but what about astrology:

Astrology as Divination

In Babylon as well as in Assyria as a direct offshoot of Babylonian culture, astrology takes its place in the official cult as one of the two chief means at the disposal of the priests (who were called bare or “inspectors”) for ascertaining the will and intention of the gods, the other being through the inspection of the liver of the sacrificial animal

The gods were also believed to present themselves in the celestial images of the planets or stars with whom they were associated. Evil celestial omens attached to any particular planet were therefore seen as indications of dissatisfaction or disturbance of the god that planet represented. Such indications were met with attempts to appease the god and find manageable ways by which the god’s expression could be realised without significant harm to the king and his nation.

An astronomical report to the king Esarhaddon concerning a lunar eclipse of January 673 B.C. shows how the ritualistic use of substitute kings, or substitute events, combined an unquestioning belief in magic and omens with a purely mechanical view that the astrological event must have some kind of correlate within the natural world:

This is interesting:

… In the beginning of the year a flood will come and break the dikes. When the Moon has made the eclipse, the king, my lord, should write to me. As a substitute for the king, I will cut through a dike, here in Babylonia, in the middle of the night. No one will know about it.

Planets and gods

Of the planets five were recognized—Jupiter, Venus, Saturn, Mercury and Mars—to name them in the order in which they appear in the older cuneiformliterature; in later texts Mercury and Saturn change places.

These five planets were identified with the gods of the Babylonian pantheon as follows:

  • Jupiter with Marduk,
  • Venus with the goddess Ishtar,
  • Saturn with Ninurta (Ninib),
  • Mercury with Nabu (Nebo),
  • Mars with Nergal.

The movements of the Sun, Moon and five planets were regarded as representing the activity of the five gods in question, together with the moon-god Sinand the Sun-god Shamash, in preparing the occurrences on earth. If, therefore, one could correctly read and interpret the activity of these powers, one knew what the gods were aiming to bring about.

System of Interpretation

The Babylonian priests accordingly applied themselves to the task of perfecting a system of interpretation of the phenomena to be observed in the heavens, and it was natural that the system was extended from the moon, sun and five planets to the more prominent and recognizable fixed stars.

The interpretations themselves were based (as in the case of divination through the liver) chiefly on two factors:

  • On the recollection or on written records of what in the past had taken place when the phenomenon or phenomena in question had been observed, and

  • Association of ideas – involving sometimes merely a play upon words – in connection with the phenomenon or phenomena observed.

Thus, if on a certain occasion, the rise of the new moon in a cloudy sky was followed by victory over an enemy or by abundant rain, the sign in question was thus proved to be a favorable one and its recurrence would thenceforth be regarded as a good omen, though the prognostication would not necessarily be limited to the one or the other of those occurrences, but might be extended to apply to other circumstances.

On the other hand, the appearance of the new moon earlier than was expected was regarded as unfavourable – as in, it happened hear a defeat in battle, death of cattle or bad crops etc.

In this way a mass of traditional interpretation of all kinds of observed phenomena was gathered, and once gathered became a guide to the priests for all times.

I’d say this clearly shows the “gathering of a theory” rather than specific astronomical event already having meaning like today.

Also, these omens were considered much more generally:

we must descend many centuries and pass beyond the confines of Babylonia and Assyria before we reach that phase which in medieval and modern astrology is almost exclusively dwelt upon—the individual horoscope.

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