It’s been a while since I wrote a recommendation post, so I figured why not break that streak with what I think is the best book on astrology you’re likely to find.

On the Heavenly Spheres by Helena Avelar and Luis Ribeiro is, as its subtitle says, a treatise on traditional astrology. Specifically, this is traditional, Western astrology which consists of techniques and concepts as practiced and understood in Europe from the Hellenistic era through the sixteen hundreds.

It’s the astrology of the middle ages and the renaissance. The stuff John Dee used to select the date of Elizabeth I’s coronation, and the stuff William Lilly wrote about in the first English-language textbook on astrology.

Simply put, it’s the heart and soul of Western astrology, and On the Heavenly Spheres does a fantastic job of presenting it. It includes traditional interpretations of the planets, signs, houses, and aspects just as you’d expect, but it also goes into incredible detail on a number of astrology’s finer points. Concepts such as sect, hayz, occidental and oriental planets, and countless others are introduced and explained in detail.

And it’s that level of detail which raises one of the two issues you might find with this book. At only around 270 pages, On the Heavenly Spheres is extremely “information dense.” Topics are introduced, discussed at length, then the authors move on assuming you have absorbed the material. This makes the book an invaluable resource, but it also might make it a little less friendly for the beginner.

Simply put, this book requires work. It demands to be read more than once, and you’ll likely find yourself referring back to it over and over again.

The second issue is less of a problem and more an intention. This is a book on traditional astrology, and the authors are both very clear on this, as well as very exclusionary of “modern” astrological contributions. The most obvious example of this is an appendix in the back of the book which criticizes the use of the outer planets Uranus, Neptune, and Pluto.

That may put some readers off, particularly if they’re coming from a purely modern background, but Avelar and Ribeiro’s arguments are worth reading.

And, at the end of the day, you’re ultimately free to take them or leave them.

No matter what your astrological background, though, I can’t recommend this book more highly. It absolutely belongs on the shelf of everyone who is serious about astrology.