We cannot deny that bodies acquire certain tendencies from heredity, but those tendencies only mean the physical configuration, through which a peculiar mind alone can act in a peculiar way. There are other tendencies peculiar to a soul caused by its past actions. And a soul with a certain tendency would by the laws of affinity take birth in a body which is the fittest instrument for the display of that tendency. This is in accord with science, for science wants to explain everything by habit, and habit is got through repetitions. So repetitions are necessary to explain the natural habits of a new-born soul. And since they were not obtained in this present life, they must have come down from past lives.