David McCann writes of profections:
"Profections (originally also called progressions) are a predictive technique involving a regular change in the ruler of a significator. When the radical Sun is in Scorpio, he will be treated as being in Sagittarius for the 2nd year (and also the 2nd month) of life, in Capricorn for the 3rd, and so on.
Ptolemy used profections only as a secondary factor in evaluating the directions of the significators: if the ascendant were directed to the square of Saturn, this would be less threatening if its profection were Cancer rather than Capricorn"
(Extracted from Traditional Astrologer Magazine; # 10, Autumn 1995, p.25)