I have always been a "what it is" and "how it is" kind of person - never a "why it is" type. This might be because I have been involved in the financial markets for the duration of my career. Most successful traders are not afraid to investigate and deploy methods not taught in schools - as long as they work.
As an astrology student, this means if I learned about a particular timing technique, I needed to understand WHAT I was working with and HOW it worked. So comparing my natal horoscope with 50 or 100 events using a dynamic quad wheel - progressions, solar arc directions, transits - was a starting place. Only by taking the time to test events did I realize that accidents tended to happen when malefics transited one of two Mars-Saturn lots assigned to the 6th house of illness and the 12th house of hospitalization. Not transits to the Ascendant degree, Moon, or Sun. And not just ‘near the lot’ but a transit within 5-10 minutes of degree to the exact lot position. This measurement precision assumes birth time accuracy of a few seconds. Findings like this, repeated for horoscopes of dozens of public figures, led to my conclusion that an AA-rated horoscope from Astrodatabank is no guarantee of sufficient accuracy necessary for serious astrological research. Hence I needed to tackle rectification.
Rectification is the reverse engineering of unknown birthtimes by matching actual life events to a theoretical birth time via astrological predictive methods. Rectification assumes the ability of horoscopes to predict the future; for those astrologers who believe in free will and eschew prediction, rectification is of no use. But for those of us who choose to go down the rabbit hole, we need to hone our skills in delineation (“WHAT the chart says”) and prediction (“WHEN it will happen”).
For many people, rectification fine tunes a birth time by a minute or less which has the benefit of increased accuracy of predictions made by directions - whose ‘hit date’ moves aproximately 1 year for every 4 minutes of birth time error. For others, birth times are rounded to the nearest 15 minutes, nearest hour, or are not recorded. Both categories of horoscopes can benefit from rectification.
When I started to work on my rectification book in 2005, the modern astrological rectification toolbox was limited to secondary progressions, solar arc directions, and transits. Since that time, the revival of traditional astrology has uncovered multiple predictive techniques, some unknown for centuries. Not all predictive techniques require an accurate to-the-second birthtime - but some do. Understanding how these techniques work - and how to layer them in the proper sequence for rectification - is what you will find in my book A Rectification Manual: The American Presidency.