Hence one whose fire is burned out is reborn through the tendencies in mind; according to his thoughts he enters life. But linked by the fire with the Self, this life leads to a world of recompense. – Prashna Upanishad.Dust thou art and to dust thou shalt return. – Genesis
The above quotation from Prashna Upanishad gives the old doctrine, the same as in Buddhism, that re-birth is due to mind and to the tendencies therein. "Whose fire has burned out" means the fire of life expiring. "According to his thoughts" does not refer to what one wishes to have for rebirth, but to the seeds of thought left in the mind from the thinking of each hour of life; these in a mass make a tendency or many tendencies which on coming out either keep the soul to that family in all modes of thought and act or tend to segregate the soul from the circle into which it was born. "This life leads to a world of recompense", because by the fire of life it is linked to the Self, which being thus bound goes after death to the state where recompense is its portion. The alternation to and fro from one state to another for purposes of compensation is not the attainment of knowledge but the subjection to results eternally, unless the soul strives to find the truth and becomes free, and ceases to set up causes for future births. A Jewish tradition says that Adam had to reincarnate as David and later as the Messiah; hence "to dust thou shalt return".