Is there a concept of sudden enlightenment or realization in Theravada? If so, how does this fit in with the Buddha's gradual path approach?
Capacities? Capacities? Capacities?
http://www.accesstoinsight.org/lib/auth ... 90.html#ii
Anguttara Nikaya, Catukka-nipata, No. 167.
...once the Venerable Maha Moggallana went to see the Elder and said to him:
"There are four ways of progress, brother Sariputta:
difficult progress, with sluggish direct-knowledge;
difficult progress, with swift direct-knowledge;
easy progress, with sluggish direct-knowledge;
easy progress, with swift direct-knowledge.
"By which of these four ways of progress, brother, was your mind freed from the cankers without remnants of clinging?"
To which the Venerable Sariputta replied: "By that of those four ways of progress, brother, which is easy and has swift direct-knowledge."
The explanation of this passage is that if the suppression of the defilements preparatory to absorption or insight takes place without great difficulty, progress is called "easy" (sukha-patipada); in the reverse case it is "difficult" or "painful" (dukkha-patipada).
If, after the suppression of the defilements, the manifestation of the Path, the goal of insight, is quickly effected, the direct-knowledge (connected with the Path) is called "swift" (khippabhiñña); in the reverse case it is "sluggish" (dandabhiñña).
In this discourse the Venerable Sariputta's statement refers to his attainment of arahantship.
His attainment of the first three Paths, however, was, according to the commentary to the above text, connected with "easy progress and sluggish direct-knowledge."
Then the Blessed One said thus to venerable ânanda: "ânanda, is Sàriputta pleased with you too?"
"Venerable sir, how could venerable Sàriputta be displeased with someone, who is not a fool, not corrupt, not erring and thinks in a constructive way? Venerable sir, venerable Sàriputta is very wise, has a wide understanding, is quick witted, has keen intelligence, has sharp and penetrating wisdom, has few desires, is satisfied, is secluded and without associations, with aroused effort, particular about his observances, speaks gently, exhorts reprovingly, disapproves evil, so why should venerable Sàriputta be displeased with someone, who is not a fool, not corrupt, not erring and thinks in a constructive way."
http://www.accesstoinsight.org/lib/auth ... html#fn-14
The wanderer replied: "I am called Upatissa, friend. Please tell me according to your ability, be it much or little. It will be my task to penetrate its meaning by way of a hundred or a thousand methods." And he added:
"Be it little or much that you can tell,
the meaning only, please proclaim to me!
To know the meaning is my sole desire;
Of no avail to me are many words."
In response, the Elder Assaji uttered this stanza:
"Of all those things that from a cause arise,
Tathagata the cause thereof has told;
And how they cease to be, that too he tells,
This is the doctrine of the Great Recluse."
Upon hearing the first two lines, Upatissa became established in the Path of stream-entry, and to the ending of the last two lines he already listened as a stream-winner.
Contrast with Story of Culapanthaka Thera