Friends:
 

What is the Investigation (Vicaya) Link to Awakening!

Investigation of states Link to Awakening (dhammavicaya-sambojjhanga)
is basically the same mental property (pañña-cetasika), that Understands
everything and which also is inherently included in the:

The Understanding feet of force (vimamsiddhipāda)
The Ability of Understanding (paññindriya)
The Power of Understanding (paññabala)
The Right View Path Factor (sammā-ditthi-magganga)

Trained, developed and refined in a degree that completely Enlightens!
If one single quality should be pointed out as thee cause of Awakening,
then it is this Investigation of states Link to Awakening that Enlightens!

The Buddha once said: What mental fermentations (āsava) should be
overcome by development? If a Bhikkhu by careful & rational attention
develops an Investigation of states Link to Awakening based on seclusion,
disillusion, ceasing, & culminating in relinquishment, then neither can any
fermentation, nor any fever, nor discontent ever arise in him. MN2 [i 11]

Remaining thus aware, then he examines, analyzes, & comes to understand
that quality with penetrating insight. While thus aware, exploring into,
examining, analyzing, & coming to full intuitive comprehension, then this
Investigation of states Link to Awakening becomes aroused. He develops
it, & for him it goes to the culmination of its development. MN118 [iii 85]

The Ability of Investigation of states is to examine, scrutinize & analyse
any chosen object & when this ability is unshakable and unfailing, it then
becomes a Power of Investigation of phenomena! By thorough and eager
investigation one understands that all things are caused and conditioned
and as such only are compounded constructions, that pass through the
inconceivably rapid moments (10-43 sec.) of arising, presence, & ceasing!
Remaining neither the 'same' nor 'stable' for two consecutive moments...
Comprehending this universal flux gradually disables clinging & craving...
Therefore do not trust anything (especially not 'your-self'!) blindly...,
but keep on examining and question what is doubtful & not quite clear.
The Investigation of states Link to Awakening is the sword that cuts
through the jungle of views to real seeing, understanding and knowing:

The last five (III-VII) of these Seven Purifications:
I: Purification of morality (sīla-visuddhii)
II: Purification of mind (citta-visuddhi)
III: Purification of view (ditthi-visuddhi)
IV: Purification by overcoming doubt (kankhā-vitarana-visuddhi)
V: Purification by knowledge & vision of what is path and not-path
VI: Purification by knowledge and vision of progress on the path.
VII: Purification of knowledge and vision (ñānadassana-visuddhi).

The Three Comprehending Contemplations:
Contemplation of Impermanence (aniccānupassanā)
Contemplation of Suffering (dukkhānupassanā)
Contemplation of Impersonality (anattā)

The 9 kinds of real Insight-Knowledge consisting in directly Knowing:
1. Contemplation of Arising and Ceasing (udayabbayānupassanā-ñāna)
2. Contemplation of Instant Dissolution (bhangānupassanā-ñāna)
3. Contemplation of Appearance as Terror (bhayatūpatthānā-ñāna)
4. Contemplation of Danger (ādīnavānupassanā-ñāna)
5. Contemplation of Disgust (nibbidānupassanā-ñāna)
6. The Desire for mental Release (muccitu-kamyatā-ñāna)
7. Reflecting & repelling contemplation (patisankhānupassanā-ñāna)
8. Equanimity regarding all constructions (sankhārupekkhā-ñāna)
9. Adaptation confirming to the absolute truth (saccānulomika-ñāna).

Further inspirations on this probing quality of Investigation of states:
Feeding Investigation: http://What-Buddha-Said.net/drops/III/Feeding_Investigation.htm
Not Examining!  http://What-Buddha-Said.net/drops/II/Because_of_Not_Examining.htm