The purpose of entire practice of dharma is to attain buddhahood. There is no other purpose.
And the purpose of attaining buddhahood is to assist all sentient being to attain buddhahood. There is no other purpose.
The purpose of all sentient being to attain Buddhahood is because it is their destination.
It is their destination because it is their potential. It is their essence. And until that potential and essence is fully matured, they will not stop suffering.
Tai Situ Rinpoche
source: http://www.palpung.org/english/special/mahamudra/brief.asp
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