I would like to dedicate my first writing to those interested in astrology who want to gain a deeper understanding of its foundations—where the system comes from and how it works. Do the planets control our lives? Do things happen to us because of the planets? Is everything written in the stars? The vernal point no longer coincides with the Aries constellation—so how can this system even work? The geocentric worldview has long been disproven, yet why do horoscopes still use it?
"That which is below is like that which is above, and that which is above is like that which is below. Thus you will understand the miracle of the One."
(Hermes Trismegistus)
First, it is important to note that astrology is a symbolic system, working with symbols, archetypes, and primordial qualities and elements that describe and operate within the world. It is crucial to distinguish between the concepts of constellation and zodiac sign, as one is astronomical while the other is used in astrology.
While constellations are shapes formed from actual stars visible in the night sky, zodiac signs derive from an imaginary division of the ecliptic, the Sun's apparent path as seen from Earth, into twelve equal 30-degree segments. Astronomers use constellations as a coordinate system to determine planetary positions in the celestial sphere—thus an uneven spatial division, which we call the astronomical zodiac. In contrast, the zodiac used in astrology—the tropical zodiac—is a temporal division derived from the solar year, dividing the Sun’s path into twelve equal units corresponding roughly to months. As the name suggests, this system is based on the Sun’s turning points (tropical helios = Sun’s turning points), aligned with the summer and winter solstices and the spring and autumn equinoxes. The solar year begins at the vernal equinox, marked as 0° Aries (zodiac sign), which does not coincide with the beginning of the Aries constellation. Naturally, the similarity in names between the two zodiacs is not coincidental. To understand this, we must travel back in time.
The first star lists (astrolabes) come from Babylon around the 12th century BCE. Some constellation names, such as the Bull of Heaven, Libra, and Scorpio, were already present. A complete list of the twelve zodiacal constellations comes from 687 BCE, recorded in the MUL.APIN series of tablets. The twelve equal-sign divisions of the zodiac appear for the first time in a text from the 5th century BCE. Cultural exchanges between Babylon and Greece likely facilitated the transfer of this system to the Greek astronomical school of Meton and Euctemon. Euctemon was the first to introduce the tropical zodiac around 432 BCE, dividing the year into 12 months named after the zodiac signs, presumably based on Babylonian sources.
"…Euctemon named the months of the tropical calendar after the twelve constellations of the zodiac, following the principle of 'as above, so below,' characteristic of Greek thought in antiquity—arguing through analogy. In other words, the division of the solar year into twelve segments, as shown by the tropical calendar, was likely seen by Euctemon as analogous to the twelve divisions of the celestial sphere visible in the zodiacal constellations."
However, this structure was not yet used for recording planetary positions; it served primarily as a calendar closely linked to seasonal changes.
The introduction of the tropical zodiac as a coordinate system is attributed to Hipparchus in the 2nd century BCE.
"For Euctemon, the equinoxes and solstices were points in time from which to begin calculating the days of solar months. Hipparchus, however, projected the equinoxes and solstices onto the sky, using them as spatial references for measurements, rather than relying on fixed stars of the zodiac as the Babylonians did."
He likely fixed the vernal point at 0° Aries, marking the beginning of the Aries zodiac sign—not the Aries constellation. Around 140 BCE, the vernal point was at 5° of the Aries constellation, and by 220 CE, it coincided with the start of the Aries constellation. Ptolemy adopted this method, describing it in his astrological work Tetrabiblos around 150 CE. He wrote:
"For astrological purposes, it is better for man to rely on this movable, artificial zodiac."
Why? Because the four elements—Fire, Water, Air, Earth—enter our world through the solstices and equinoxes: Fire at the spring equinox, Water at the summer solstice, Air at the autumn equinox, and Earth at the winter solstice. The active, expansive, bursting energy of Aries is triggered at the vernal point on Earth. We feel and see Aries energy manifesting around us; a new life cycle begins, buds sprout, flowers break through the hard soil, life awakens. To imagine the temperament of an individual with prominent Aries energy, picture a true spring day: active, mobilizing, ready for action, courageous, initiating, and energetic. Other signs similarly connect with the energies manifesting on Earth, and observing planetary positions in our environment, why would we think they have no effect on us?
The 12 zodiac signs are determined by three factors: the element (Fire, Earth, Air, Water), the quality (cardinal, fixed, mutable), and the polarity (positive/outgoing or negative/incoming).
The elements were first described by Empedocles in the 5th century BCE in Tetrasomia as the roots of all things, proposing that the universe arises from their combinations. Aristotle later assigned two properties to each element, choosing from hot, cold, wet, and dry.
Qualities express dynamics and vibrational variations. Cardinal is initiating and creative, fixed is retaining and preserving, and mutable is adaptable and transformative. For anything to manifest, cardinal quality is needed. Without fixed quality, it would vanish immediately; without mutable quality, nothing would change, so all three are essential.
Polarity expresses a sign’s activity: positive signs are proactive and initiating, while negative signs are reactive, adaptive, and responsive.
These elements, qualities, and polarities define the zodiac signs, forming a beautiful system that not only reflects an individual’s personality and energy patterns but also describes the human life process. Humanity as a whole progresses through the zodiacal cycle. Thus, we see how the meaning of a constellation differs from that of a zodiac sign.
Our personal horoscope reflects the imprint of the time quality at the moment of birth. Since we observe planets from Earth, our horoscope maps the sky at our birth, making the radix geocentric. Planets do not cause events; planetary positions indicate what is “above,” and by analogy—"as above, so below"—we perceive the effects. Just as polarity manifests on Earth, determinism and free will coexist: we receive a framework and energy pattern that we cannot change, but how we use it, what we make of it, and how much effort we put into self-knowledge and growth is up to us. A knife can be used to harm or to cut bread for the hungry—this is our free will.
Sources:
Robert Powell: The History of the Zodiac
Stephen Arroyo: Astrology, Psychology, and the Four Elements
Ervin Baktay: The Book of Astrology
Brigitte Hamann: The Twelve Archetypes
Claudius Ptolemaeus: Tetrabiblos
Rafael Csaba: The Philosophy of Astrology (lecture)
[1] Robert Powell: The History of the Zodiac, p. 26
[2] Robert Powell: The History of the Zodiac, p. 49
[3] Ptolemy: Tetrabiblos, I, 22
[4] Stephen Arroyo: Astrology, Psychology, and the Four Elements, p. 37