'It is through not understanding, not penetrating four things that we have run so erratically, wandering on so long in this round of existence, both you and I. What are the four? Goodness, concentration, wisdom, and liberation. When these four things are understood and penetrated, craving for superficial existence is rooted out and that which leads to continued return to the same conditions is ended. There is no more constant journeying.'
- Digha Nikaya in The Buddha Speaks, A book of guidance from the Buddhist scriptures, edited by Anne Bancroft.