Until the 21st Century synastry and secondary progressions were separate things in astrology. In 2002 if you typed the string "progressed synastry" into Google, you would get one result - my website. Today you get 22,800.

Progressions were first described in the second century by Vettius Valens, a younger contemporary of Claudius Ptolemy, and then possibly by Johannes Kepler in the early 17th Century. Their modern usage dates from 1657 when Placidus de Titis described them in his book Primum Mobile. Synastry (how birth charts combine in relationships) has been thought about for millennia. 

The first published mention of progressed planets being important in synastry was put forward by Penny Thornton in her 1982 book Synastry. This was echoed in the next decade by Fred Gettings, Marion March & Joan McEvers, and in 1997 by Robert Blaschke. All of these authors noted either that progressed planets might be involved in synastry or that very often progressed planets are involved at the time of a meeting. All of the authors seem to have noted this as an interesting anomaly and something that is an adjunct or add-on to natal synastry. None appear to have published research on the subject.

My introduction to this subject was not influenced by these authors, it was a purely practical exercise. I noted a comment by Laurie Efrein in her book How to Rectify a Birth Chart in 1988 (I can precis this as 'transits happen to you, progressions change you.') and made an assumption that progressed planets were intrinsic to synastry. When I noticed an interesting Venus trine in my relationship in 1997 it started me on a path of research which became a 23-year experiment.

I named Progressed Synastry (another suggestion was synastric progressions, but Robert Blaschke did not want anyone else to use this phrase, and temporal synastry was suggested by Dennis Elwell) and developed it between 2000 and 2006 from the point of view that if it works it should radically change our view of astrology and how it should be taught and practiced. This is because if it works, it shows that horoscopes change. This is fundamentally opposed to the idea that birth charts are fixed and static entities and challenges the assumptions made by astrologers for two thousand years.

I first published an article 'Why Do Lovers Break Each Other's Hearts?', which set out my initial discovery in The Mountain Astrologer in October 2003, using historical examples and which was based on the first 700 relationships I had examined. This article created a stir and 0.1% of the TMA readership wrote to me expressing in most cases admiration and encouragement, but there were also some corrective comments including one person who insisted John Lennon was born in Manchester.
This article was written in late 2002 but took a year to publish.

I secured a publishing deal in 2005 with the help of Adam Fronteras and my first book on the subject was published in September 2006 through O Books. There were problems with printing (Adam and I both advised the publishers that the date they had chosen was not good, but astrologers don't often get listened to by publishers). The first print run had to be pulped because the printers had been sent the wrong PDF by the designer and the matrices in the book were not highlighted correctly. 500 of these books were distributed by the time this was noticed, so if you have one, it's rarer than the correctly printed version. Because of this, publicity was canceled, and when the second print run took place in January 2007 it was too late to do much about it. So, When Stars Collide had to rely on word of mouth, and now sixteen years later it's still a book that won't stay on the shelf for a lot of astrologers.

I developed a method of automating graphs and reports for progressed synastry with Allen Edwall and later carried out a repeat of my initial experiment utilizing ever larger control groups. A group of skeptics led by Geoffrey Dean has unsuccessfully attempted twice (in two versions of the same book) to theoretically argue that my results are somehow 'wrong', without actually doing any work to demonstrate this or coming up with a cogent reason why. 

Paul Westran