Generally speaking, it is very difficult to directly prove the existence of causality because our eyes cannot look beyond this present life for causes from previous lives and the effects in future lives. Nonetheless, through indirect means it is possible to prove the link between cause and effect. Not only is samsara conditioned by causality, but also nirvana and liberation. Therefore, if it is liberation that we seek, we must plant the seed of liberation, which will then yield the fruit. Such is the view of Buddhism.

~ Luminous Wisdom 1: On Cause and Effect