Book Reviews

Decanates & Duads

The Zodiac Within Each Sign

Frances Sakoian & Louis Acker


Intermediate to professional


Egyptian astrological concepts written in Modern Humanistic style

Frances Sakoian & Louis Acker wrote so many seminal astrology texts in the latter half of the 20th century. If you learned astrology back then, you no doubt had a copy of one of their books in your library, and it was probably ‘The Astrologer’s Handbook‘. They also wrote on relationships, predictive techniques, aspects, transits…I could go on, they were prolific and you should absolutely check them out if you haven’t already. But it is this little gem of a book that is the most well-thumbed of my Sakoian-Acker books – ‘Decanates and Duads’.

What on Earth?

If you’ve ever wondered what those lines are for around the edge of astrology chart wheels, this is the book for you. ‘Decanates and Duads‘ explains very simply how to get even more context out of an astrology chart. These ancient Egyptian time markers can provide terrific insight into why, say, twins born a minute or two apart can be totally different in so many ways, even though their natal charts seem identical on first glance.

But what. On. Earth.

A brief pictorial – decanates and duads (also spelt dwads) are the tiny little lines or semi-segments around the outer wheel of the chart. Decanates are each 30º sign cut into 3 segments of 10º. Duads are slicing the 12 signs into 2.5º segments.

My first astrology teacher LOVED decanates. In hindsight we spent quite a bit of time learning them, and the Sabian Symbols too, so I automatically calculate them in my head when looking at a chart. Decans are quite straightforward, viewed through triplicity rulers, that is fire – Aries, Leo, Sagittarius; earth – Taurus, Virgo, Capricorn; air – Gemini, Libra, Aquarius and water – Cancer, Scorpio, Pisces. So 8º Aries is in the Aries decan, 13º Aries is through the Leo decan and 26º Aries is through the Sagittarius decan. Simple enough, yes?


The duads get the brain working a little harder. They move consecutively through the signs, not via triplicity. It’s actually not hard to get your head around this, it’s the math that gets me every time. Two and a half degrees. 2.5º! Seems simple enough…perhaps it’s just me. Anyway, using the above examples again to show how it’s done- 8º Aries is viewed through the Cancer duad, so add a little emotional intensity. 13º Aries is in the Virgo duad, giving a little more thought to the usual Arian ‘do first, think later’ life motto. 26º Aries is flavoured with Aquarian duad sauce, colouring Aries reckless abandon with determined individuality. See, a little more thinking but plenty of insight for the effort.

We look to planetary rulerships for more information- Taurus is ruled by Venus, Gemini is ruled by Mercury etc. The first decan and first duad are always the most potent, they are a triple threat – 2 degrees Virgo is in the decan of Virgo, and the duad of Virgo, thus Mercury ruled and then some. Don’t overthink it! Unless you have a triple Mercury ruled sign – decan – duad. If so, don’t let the rest of this book review stand in your way. Go for it! Though you are probably ordering the book right now whilst simultaneously googling for more info and messaging your astro group chat to see if anyone else uses decanates and duads.

And the book?

Yes, the book. It is concise, running to 116 pages. There is a brief interpretation of the relevant zodiac sign at the beginning of each chapter and then we get straight into the decanates and what they indicate. Understanding rulerships is integral to getting the most out of the concepts presented in this book. Both modern and traditional rulerships are used throughout the book, for example Jupiter rules both Sagittarius and Pisces. I like this. I lean to traditional rulerships but it is always interesting to read or hear about modern rulership interpretations because it’s good to know that Uranus is considered exalted in Scorpio. I need to now investigate why this is so, but it’s food for thought. No judgement.

While ‘Decanates and Duads’ it may seem a little like chart overkill or adding complications at first, it is actually a terrific way to narrow in on the character of a client. It would definitely be useful when rectifying a chart, though I haven’t tried this technique. I do find it of particular use when working with annual profection time lords and the progressed moon. This book is useful, the whole concept of decanates and duads is pretty basic, despite my complaints about math, and doesn’t require complicated programs to work out what is where and when. All the information you need is already there, in the chart. I mean, if you’re going to add asteroids and fixed stars, you may as well start with what is right there in the chart first, no?

This book was published in 2009, quite a few years after Frances Sakoian passed. You can check out Louis Acker’s astrological work here and according to his website, he is still taking bookings for chart readings –

Must. Own. Decanates and Duads.

Decanates and Duads: the Zodiac Within Each Sign is available at the usuals – Book Depository and Amazon in hard copy only.


Other than the Foreword & Introduction this book goes through each of the signs of the zodiac, from Aries through to Pisces, and breaks them down into roughly 5 pages each sign. In 116 pages, you get a triple layer of insight into each sign, point and planet of a chart.


No index. Sigh. Luckily it’s not a lengthy book.


American Federation of Astrologers, Inc.

Tempe, Arizona