AUTHOR’S NOTE: There is apparently an ongoing controversy among the upper echelon of professional astrologers regarding which system of house division came first, the “quadrant” system later popularized by Placidus de Titis or the Whole Sign system. In the time-based method of Placidus, the Ascendant is coincident with the 1st House cusp and the intermediary cusps are derived by trisecting the elapsed time between the Ascendant and the Midheaven (the calculated 10th house cusp) on the day of birth and converting the results into degrees of arc using proportional logarithms, then extrapolating from there to create twelve houses of varying size. The Whole Sign house system places zero degrees of the sign containing the Ascendant on the 1st House cusp, and zero degrees of the following signs on the remaining houses, such that the Ascendant and the rest of the axial points – Descendant, Midheaven and Imum Coeli – will fall somewhere within the houses so defined rather than directly on their respective angles at most latitudes. In this system all houses are of equal size and encompass an entire sign.

Placidus de Titis lived in the 17th Century, but Hebrew sage Abraham Ibn Ezra is said to have noted in the 12th century that the method of horoscope division exemplified by Placidus was in fact employed by 2nd Century Greek astrologer Claudius Ptolemy. Others have said that the Whole Sign technique originated in the Arab world between the 9th and 11th Centuries and was grafted onto the work of Ptolemy. A third opinion is that the Hellenistic astrologers used the Whole Sign and Equal House systems because they didn’t have the mathematical sophistication and scientific tools to accurately calculate or measure degrees of arc as a function of time. I can’t vouch for the validity of any of these arguments, but I do believe that both systems have their merits and splitting hairs about which came first is largely moot. For those who are interested, classical astrologer Chris Brennan wrote a thorough article about Ptolemy’s preferred method of house division in 2011. The conclusion was that he most likely used Whole Sign houses for most purposes, limiting the practice of “quadrant-based” house division (similar to that of Placidus) to “length-of-life” determinations. Thus it appears that both techniques coexisted in Ptolemy’s approach to the astrological houses.

I use Placidus for natal work but also look at the Whole Sign chart; the degrees on the axes don’t change, just the house cusps, and therefore the planetary domiciles will often shift. Placidus houses (and those of similar systems) have the disadvantage of creating “intercepted” charts at higher latitudes (due, I believe, to the fact that the Earth isn’t a perfect sphere), in which a house can be larger than 30 degrees and “swallow” an entire sign; but with Whole Sign houses we frequently have to rethink planet-in-house delineation because the map can change. It’s an interesting exercise to do on one’s own chart. For horary I follow John Frawley and use Regiomontanus. I’ve also used the Koch system for natal work, but not for many years now. Back in the 70s everyone was taught Placidus, and only the renewed interest in classical astrology brought Whole Sign (as well as Equal House) division to the forefront. I have also experimented with the ancient Greek “octile” system which apportions the horoscope into eight 45-degree segments, in line with the German idea that the “hard” aspects (45, 90, 135, 180) are the most active and eventful. In this concept, quadrant emphasis similar to the innovations of 20th Century astrological pioneer Marc Edmund Jones replaces the “department of life” focus of traditional houses.