To clarify astrological terminology it is perhaps well to emphasize a distinction between these two terms so often loosely applied to the same process: Directions, to indicate the theoretical advance of some one body or point in a chart, by applying to it an arc of direction for a given period of time, or by measuring the arc between it and some other sensitive point, cuspal point or place formerly tenanted by a planet, and by reducing it to time by some such measure as that employed in the Primary System of Directions. Progressions, indicating the advanced positions of the Ascendant, Midheaven and planets as shown in a Progressed Figure cast for a given date, as employed in the system of Secondary Progressions (q.v.). Alan Leo employs both terms rather indiscriminately, defining Directions as "calculations made from the Nativity for the purpose of ascertaining the time when events will happen. Properly speaking this is predictive Astrology, since it is concerned with the future of the person for whom the calculations are made. Directions are classed under two heads: Primary and Secondary. The former is similar to the small hand of a clock which marks off the hours, while the latter are like the long hand which marks off the exact time."
Although Alan Leo wrote an imposing volume on the "Progressed Horoscope" he says in his Dictionary that "the question of the progressed birthday at the rate of a day for a year needs investigation."
