When a planet is in its depression or deepest fall, the period assigned to it is reduced by half; if it occupies an intermediate position, the reduction shall be proportionate. The number of years given by the Lagna correspond to the number of its Navamsas that have risen above the horizon. According to some the Lagnayus is as many years as there are Rasis from Mesha up to the Lagna. The planets except when their motion is retrograde lose a third of their Ayurdayas when in inimical houses. When they are eclipsed, their Ayurdaya is to be diminished by half. This last reduction does not apply to Venus and Saturn.