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(religion, spiritualism, and occult)

The Hyleg (Arabic), Apheta (Greek), Prorogator (Latin), or Giver of Life, was a planet or point that was calculated as part of the process to evaluate both the life expectancy and periods when the native was at mortal risk. When this point was directed (using what are now called primary directions) to an Anareta (or killing point; there may be more than one), or vice versa, death occurs. In their book Greek Horoscopes, Otto Neugerbauer and Henry Bartlett Van Hoesen noted that early versions, such as that of the Roman astrologer Babillus, allowed any planet to be hyleg; later versions restricted the hyleg, except under relatively rare circumstances, to being one of the hylegical points: Sun, Moon, ascendant, or Part of Fortune.

House placement is critical to the definition of the hyleg. The earliest Greek houses were what is now referred to as whole sign: if the ascendant was in Cancer, then the first house was Cancer, regardless of the degree of the ascendant. This is similar to traditional Vedic usage as well. In this system, the words “sign” and “house” become literally interchangeable, as in, “The Sun is in his own house” being equivalent to saying “The Sun is in Leo.” Ptolemy, who represents the later Greek period, used equal houses from the ascendant, where the first house was comprised of the region from 5° before the ascendant, through 25° after. Each of the following houses was constructed the same way. Using this definition, Ptolemy then defined the prorogational or hylegical places, or houses: the first, seventh, ninth, tenth, and eleventh houses, as noted in his Tetrabiblos. In Ptolemy’s definition, the Part of Fortune was always taken using the daytime formula; unlike many classical sources, he did not reverse the calculation by day and by night.

In calculations of the hyleg, the general procedure is to examine particular hylegical points in a given sequence. Determine if the first planet or point in question is in a hylegical house. If it is, and it meets all other specified criteria, then that body or point is declared the hyleg, and the procedure ends. If it is not, then the next body or point in the sequence is examined, then the next, as necessary.

Ptolemy’s method begins with no provision other than whether the body or point is in a prorogational or hylegical place. The sequence of placements examined depends on whether the chart is diurnal or nocturnal.

If diurnal, examine first the Sun, then the Moon, then the planet that has the most types of rulership (all five essential dignities) over the Sun, the prenatal new Moon, and the ascendant. If none of these bodies or points is in a prorogational house, then the ascendant is prorogator or hyleg.

If nocturnal, the Moon, then the Sun, then the planet that has the most types of rulership (all five essential dignities) over the Moon, the prenatal Full Moon, and the Part of Fortune. If none of these bodies is in a prorogational house, then the ascendant is prorogator or hyleg if the prenatal syzygy (i.e., lunation) was a new Moon; otherwise if the prenatal syzygy was a full Moon, use the Part of Fortune as hyleg.

Ptolemy then uses the prorogator and principally its aspects to benefic and malefic planets to calculate the length of life.

By contrast, here is the system of calculation according to Guido Bonatti, as noted in Robert Zoller’s book Tools and Techniques of the Medieval Astrologers. At Bonatti’s time, 30° houses were not used in the “placement in a house.” In Bonatti’s system, if a body was on the cadent side of an angle, it was still angular if it was within 7° of the cusp. If it was on the angular side of a succedent house, it was still succedent if it was within 5° of the cusp. And, if a planet was on the succedent side of a cadent house, it was still cadent if it was within 3° of the cusp. In this table, the hyleg is found once a statement is true.

  1. The Sun in first, tenth, or eleventh house in a masculine or feminine sign.
  2. The Sun in seventh, eighth, or ninth house in a masculine sign only.
  3. Moon is in an angular house or in a succedent house, and in a feminine sign, and possessing any of the four dignities: exaltation, trip, term, or rulership.
  4. Born on a waxing Moon: examine the dispositors of the ascendant. If any of its dispositors also aspects the ascendant, the hyleg is the ascendant; otherwise check Fortuna for an aspecting dispositor.
  5. Born on a waning Moon: examine the dispositors of Fortuna. If any of its dispositors also aspects Fortuna, then use Fortuna as hyleg; if not, check the ascendant for an aspecting dispositor.
  6. If all else fails, see what planet has dignity in the degree of the new or full Moon before birth.
  7. If none of these work, then the chart is a third differentia and the child will die before age 12.

While this might look like a very rigorous system, there is actually one point of ambiguity. In Bonatti’s original definition, it was not stated that the Sun or Moon, in order to be hyleg, also had to aspect one of its dispositors. The necessity for an aspect between any potential hyleg and one of its dispositors was made in Omar of Tiberius’s commentary, but it was initially unclear whether this was simply a variation introduced by Omar, or whether it reflected Bonatti’s actual usage. With the availability of more classical sources, it is likely that Bonatti simply gave a slightly abbreviated version of his actual working definition.

While this might seem like a relatively minor point, its significance is that one study of the efficacy of the various classical definitions of the hyleg was done, using the data from the March 13, 1996, classroom shootings in Dunblane, Scotland, in which about half the students were killed, and half were not. In an article she wrote for the January 1998 issue of the Horary Practitioner, Penny Shelton compared methods from Ptolemy, Dorotheus, Bonatti, William Lilly, John Gadbury, and Henry Coley, and found the Bonatti system to be the most satisfactory in predicting which of the children lived and which died. However, Shelton did not incorporate the necessity for the Sun or the Moon to aspect a dispositor to be counted as hyleg. So perhaps this particular restriction needs reexamination.

The later methods of Lilly, Gadbury, and Coley that Shelton included represent various simplifications of the older system. Later, the simplifications became even more extreme. For one thing, all the earlier definitions were dependent on the five essential dignities, and this became impractical once these dignities were forgotten.

In the Arabic period, the calculation of the hyleg and its derivatives became the principal system for evaluating the length of life. In the Hellenistic period, noted Neugerbauer and Van Hoesen, this function was instead derived from the position of the ascendant.

The calculation of the length of life proceeds as follows. First, Alcocoden is examined, which is the almuten of the hyleg in the case of the Sun or Moon, or the planet which is the aspecting dispositor for the Ascendant and Part of Fortune (also the Sun and the Moon). The alcocoden is also called the “giver of years” in English.

The condition of the alcocoden is then examined with respect to the Table of Years given below. If including only the major dignities (i.e., rulership, exaltation, and triplicity), the alcocoden is essentially dignified, the native’s life span is enumerated from the “old years” column. As the transition occurs to lesser dignity to no dignity, and succedent to cadent, then the starting point shifts to one of the other columns.

The final stage, as given by Omar of Tiberius, is to examine whether the alcocoden is aspected by either the benefics or malefics. In either case, an aspect results in either adding or subtracting the lesser number of years.

Table of Years

To better exemplify the success of this table, the Table on the Longevity Expectations for Czars of Russia follows. One of the reasons this particular set was selected is that, with the exception of Nicholas II, none were really subject to the modern understanding of hygiene and allopathic trauma care, which arguably could have thrown off the longevity compared to traditional expectations.

Longevity Expectations for Czars of Russia

When freed from being a system of precise longevity calculation, the system does provide some very useful information. Clearly, a person who shows a short to medium longevity is more likely to have serious health consequences earlier in life than a person with greater longevity. This can translate into the necessity of paying more attention to bodily symptoms so that serious conditions are not the only necessary outcome.

—J. Lee Lehman, Ph.D.


Ferrier, Oger. Des Jugements astronomiques sur les Nativitez. Lyon, France: Jen de Tournes, 1550.
Neugerbauer, Otto, and Henry Bartlett Van Hoesen. Greek Horoscopes. Philadelphia: American Philosophical Society, 1959.
Omar of Tiberius, Three Books of Nativities. Translated by Robert Hand. Project Hindsight, 1997.
Ptolemy, Claudius. Tetrabiblos. Translated by F. E. Robbins. Cambridge: Harvard University Press, 1971.
Shelton, Penny. “Awareness of Fate.” The Horary Practitioner January 1998.
Zoller, Robert. Tools and Techniques of the Medieval Astrologers. Privately printed, 1981.