A Brahmin Priest once asked the Blessed Buddha:
Master Gotama, what is the cause of being unable to remember even something that has
been memorized over a long period and also that which has not been memorized?
Brahmin, when mind is perplexed by doubt & uncertainty, undecided, wavering & wobbling
by doubt & uncertainty, and one does not understand any actual safe escape from this
arisen doubt & uncertainty, in that moment, one can neither see nor understand any of
what is advantageous, neither for oneself, nor for others, nor for both oneself & others!
Then, consequently, even texts, that have been long memorized, cannot be remembered…
Why is this neglect so? Imagine a bowl of that is muddy, unclear, cloudy, blurred & dark.
If a man with good eye-sight were to inspect the reflection of his own face in it, he would
neither see nor recognize it, as it really is! So too, brahmin, when mind is confused by doubt
& uncertainty, baffled, bewildered & hesitating by doubt & uncertainty, on such occasion
even texts long memorized do not recur to the mind, not to speak of those texts, events &
information, that have not been memorized at all…
On how to prevent Doubt & Uncertainty (curable vexation), details & assuring inspiration:
Systematic and Frequent Attention to scrutinizing investigation, examination & probing:
1: What is advantageous and what is detrimental here?
2: What is blameable and what is blameless in this situation?
3: What is ordinary and what is excellent in this particular case?
4: What is on the bright side and what is on the dark side specifically & in general?
Understanding is Chief:
http://What-Buddha-Said.net/drops/Understanding_is_the_Chief.htm
Hindrances - Nivaranas:
http://What-Buddha-Said.net/Canon/Sutta/AN/AN.I.3-4.htm
Medicine and Comments:
http://What-Buddha-Said.net/Canon/Sutta/AN/AN.I.3-4c.htm
Source (edited extract):
The Grouped Sayings of the Buddha. Samyutta Nikaya.
Book [V:123-4] section 46: The Links. 55: To Sangarava...
See also:
http://What-Buddha-Said.net/drops/Barren_Stagnation.htm
http://What-Buddha-Said.net/drops/II/How_to_Overcome_Doubt.htm
http://What-Buddha-Said.net/drops/II/Curing_Doubt_and_Uncertainty.htm
http://What-Buddha-Said.net/drops/IV/Suitable_Substitution.htm
