The roots of zodiac astrology reach back about four thousand years to Mesopotamia. The priests of Babylon observed the night sky with precision, divided the Sun's path—the ecliptic—into twelve regions, and read the movements of planets and stars as signs from heaven foretelling the fortunes of kings and nations. Early astrology was thus a grand study that divined the fate of the state rather than the fortune of an individual.
As this knowledge crossed into ancient Greece, astrology underwent a great turn. The Greeks clothed the planets in the names and characters of gods such as Zeus and Aphrodite (which, in Rome, settled into Jupiter, Venus, and the rest) and established today's method of reading an individual's character and destiny through the horoscope, a chart of the sky at the moment of birth. The "Tetrabiblos," written by the second-century astronomer Ptolemy, gathered this theory into one and served as the textbook of Western astrology for more than a thousand years.
In the Middle Ages astrology flourished in the Islamic world. Arab scholars carefully preserved the Greek legacy and added more refined methods of calculation, and this knowledge flowed back into Europe to become a respectable subject taught at universities. Intriguingly, astrology and astronomy were then one body, for calculating the planets' positions precisely was no different from casting a fortune. Even a great astronomer like Kepler practiced astrology as well.
The two parted only after the Scientific Revolution of the seventeenth century. As the telescope and physics advanced, astronomy took the road of a science of measurement and verification, while astrology took that of a language of symbol and meaning. Astrology, which had seemed to fade for a time, met an unexpected revival in the twentieth century. In the 1930s a British newspaper began running a sun-sign column on a celebrity, and sun-sign horoscopes spread widely into popular culture; on the other hand, under the influence of the psychologist Jung, a deeper current called psychological astrology, exploring character and the inner life, grew alongside it.
Today astrology is more familiar than ever, especially to younger generations. Apps that automatically compute complex birth charts, daily horoscope alerts, zodiac memes, and its use as "another language for understanding people" all blend together in a new heyday. Long parted from science, astrology still remains an old mirror in which we gauge our place beneath the vast sky and gently reflect on our innate temperament and the currents we will meet. Astrology shines brightest when you see the stars not as forcing you, but as an occasion to look within.