David explains how the planets, signs and houses, interact to form aspects and yogas. In Vedic astrology aspects are formed based on signs and not orbs as in Western. Also, planets do not just aspect other planets (as in Western) but aspect the house with its influence. Furthermore, in Vedic astrology the planet casts its influence forward. In Western astrology the planet casts its influence both forward and backward. David Frawley goes on further to explain another difference, that of the conjunction.