A prince who cast charts: astrology at the Portuguese court in the 1600s

Astrology in the seventeenth century was not a fringe pursuit. It was taught, practised at court, argued about by theologians, and used by governments — and Portugal after the Restoration of 1640 offers a particularly clear view of what that looked like in practice.

The heir

Dom Teodósio, born at Vila Viçosa in February 1634, was the eldest son of João IV and heir to a throne his father had just taken back after sixty years of Spanish rule. With reintegration into Spain a standing threat, an uninterrupted succession was a matter of national survival, and a great deal rested on a boy of seven.

He grew into a cultured and intellectually curious young man with decided political and religious opinions. He also had a serious interest in astrology. He is recorded as keeping a collection of his family's charts, as making predictions on political questions — including, it is said, on the fall and restoration of the English monarchy — and as receiving regular astrological reports from the most prominent practitioners of the day. A short astrological essay of his is mentioned in the sources; the manuscript has not been found.

His tutor was the Jesuit António Vieira, who studied the subject himself. That detail is worth pausing on, because it contradicts the usual story: the relationship between the Church and astrology in this period was considerably more complicated than a simple prohibition, and an interest in charts was compatible with an entirely orthodox career.

What such a chart was read for

A royal nativity was not read for character. It was read for succession, health and the fate of the kingdom, and it was read with a specific set of tools.

The almuten of the figure — the planet with most dignity over the significant places — was taken as governing the whole life, and its condition set the tone of everything else. A mutual reception by exaltation between the planets of mind and action was read as an unusually effective disposition for study. The Parts, of Spirit and of Faith, were taken seriously, and their dispositor mattered: a chart in which the same planet is the almuten, sits in its own house of joy, disposits both Parts, and rules the eighth house, is one in which religion and mortality are tied to a single significator.

That last combination is an example of how the older technique reaches conclusions modern practice has no way of stating. Dom Teodósio's tutors are recorded as warning him repeatedly about the severity of his devotions — the fasting and mortification that his biographers connect with his failing health. He died at nineteen of stomach and lung disease. A single planet carrying both his religion and his eighth house is not a coincidence a seventeenth-century astrologer would have passed over.

The techniques of the death

Four methods were applied together, and the expectation was that they would agree:

• Directions — the Ascendant arriving at a royal fixed star, and entering the terms of a choleric planet, which the tradition reads as both honours and a choleric illness;
• Profections — the profected Ascendant falling in the eighth house and applying to the lord of the sixth;
• Firdaria — a period ruled by a planet placed in the sixth house of the nativity;
• The solar revolution — where the lord of the year is afflicted, the lord of the natal sixth falls on the natal Ascendant, and the Moon lands in the house and the sign that govern the part of the body that failed.

Four independent techniques pointing at the same house and the same organs is the standard the period expected. The requirement that testimonies agree is not a modern refinement; it is how these authors worked.

The mundane echo

Because the prince's life was tied to the kingdom's, the same event was expected to appear in the mundane charts — and the partial solar eclipse of April 1652 was read accordingly, its degree afflicted by a malefic placed in the second house, which is the fifth from the tenth: the king's son.

There is a traditional reading of an eclipse in that part of Aries that speaks of a prince brought to restraint, with sorrow and danger of death. Whether one finds that persuasive or not, it is what a seventeenth-century astrologer would have found in the standard authorities, and it shows what such a person actually did with an eclipse: derive the house, identify the person, consult the received judgement.

Why this history matters

Reading the practice of a period in its own terms is not antiquarianism. It shows which techniques were relied on when something important was at stake, which is a better guide to what practitioners found dependable than any modern summary of their doctrine.

Our research includes the recovery of birth data from Portuguese chronicles and archives, with sources recorded, and the reconstruction of how astrology was actually practised here between the fifteenth and eighteenth centuries.