At various times in the history of Buddhist philosophy there have been debates about whether enlightenment is attained suddenly or gradually (dandhàbhi¤n¤a, khippàbhi¤n¤nna, Vism.85).  The moment of enlightenment is sudden, but the process of getting to that stage may be gradual. The Buddha said: `Little by little and from time to time the wise person should remove his defilements the way a smith removes dross from silver' (Dhp.239). In another place he says: `Just as the ocean slopes away gradually,  inclines  gradually without any abrupt precipice, even so this Dhamma and discipline is a gradual doing, a gradual training, a gradual practice. There is no sudden penetration of knowledge'(Ud.54).