Horoscopy is stated to be science of Ahoratri  or the science of day and night these being the broadest visible divisions of time multiples of which give weeks months years etc and divisions of which give hours minutes seconds etc The first letter A and the last legger tri having been dropped the term has assumed the shape of hora and the author says that hora Shastra treats of the effects of the good and bad deeds of an individual in his previous birth Astrology rests on astronomy The latter science was probably in a good condition at the time of Vikramarka The tables for the calculation of the places of the planets which were then framed or then in use were all suited to the time Owing probably to the wear and tear of the several working parts of the whole machinery of the Solar System the tables of one age are unsuited to another age