An objection which has been raised against the Ptolemaic system of Planetary Periods, and which on the same grounds may be raised against this one, deserves consideration. It is said that it is extremely unlikely that all persons are under the same planetary influence at the same age. In this I should concur were it intended that a single planet entered into the equation. Such, however, is not the case. For although all persons are under the influence of the Moon at a certain period of their life, and all of the same age are under the same periodic influence at the same time, yet it must be remembered that in the large variety of horoscopes which arise out of astronomical changes during even a single month, it is extremely unlikely that any number of persons of the same age were born under the same conditions, and in one horoscope we shall find the Moon afflicted, in another well aspected, and so on. Consequently, the Moon Period in these horoscopes will be variously interpreted. For if the planet governing the Period in force at any age is well placed and aspected at birth, then the period will be a fortunate one, and _vice versa_. Moreover, the sub-periods involving the introduction of a subsidiary influence into the Period will be interpreted in terms of the aspect the sub-period planet bears to the Period planet at the moment of birth, and thus an infinite variety of interpretations are afforded by the consideration of the various houses, signs and aspects held by the planets in the radical or birth horoscope. Each planet then will rule in succession for a Period of twelve years, during which it will bring into play the conditions indicated by its position and aspects at birth. The same planet will rule for the first sub-period of that Period, and will be followed by the other planets in Chaldean order. Each sub-period will extend over one year and four months, and will import an influence agreeable to the nature of the planet ruling it, as well as an influence in terms of its radical relations to the Ruler of the Period.