lent 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 proro-
gational 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 ascen-
dant is prorogator or hyleg ifthe prenatal syzygy (i.e., lunation) was a new Moon; oth-
erwise 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 Bon-
atti’s time, 30° houses were not used in the “placement in a house.” In Bonatti’s sys-
tem, 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.
- The Sun in first, tenth, or eleventh house in a masculine or feminine sign.
- The Sun in seventh, eighth, or ninth house in a masculine sign only.
- 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 ruler-
ship. - 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; other-
wise check Fortuna for an aspecting dispositor.
THEASTROLOGYBOOK [345]
Hyleg