In the same way that physical illness needs the right medication to be cured, cyclic existence can only be stopped through practicing the Dharma. To effectively counteract defilements and attachment, one must exert a sharply opposing force. The exertion of this counteracting force is the path leading to the cessation of suffering.
In other words, the purpose of undertaking Dharma practice is bring the endless cycle of rebirth and death to a halt, not unlike what the right medicine does for a patient.
~ Luminous Wisdom 1: The Four Noble Truths