The Buddha describes how the development and making a big thing of the idea of their being nothing attractive in the body, the disgusting nature of food, the thought of distaste for the world, the perception of impermanance in everything that has been own-made, and the establishment in mind of the thought of death has its fruition in freedom of heart and the advantages of freedom of heart and freedom of wisdom and the advantages of freedom of wisdom.
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Index to available translations: AN 5.71
In this sutta similes are given for such fruit and advantages: lifting the barrier (for letting go blindness), filling the moat (for ending rebirth; you need to see this from the point of view of a conqueror), pulling up the piller (for getting rid of thirst; the piller that supports the structure), withdrawing the bolts (for having broken the five fetters that bind one to the lower births; the bolts that lock the door of escape), being an Aristocrat that "lowered his standard" (dipped his battle flag as a sign of surrender) and dropped the burden (an image that goes against the grain but here standing for giving up the battle to asert a self, for he has let go of the mental derangement: 'I am!').
An interesting thing to note about this sutta is that these are all things which are to be 'pahiinaa', 'let go'.
Letting go is a thing that is accomplished by no longer keeping a grip on.
It just requires stopping.
Hold an egg in your hand and then relax all the muscles of your arm and hand.
What struggle is involved is not a matter of acquiring something, it is a matter of dealing with one's reluctance to stop indulging in participation.
The implication is virtually identical to the Buddha-nature of the Zen Buddhists and Mahayanists, that is, that awakening occurs at the point when one is rid of obstructions, but with the all-important difference that in the Zen/Mahayanist way of thinking this is a state that is achieved, and by an individual, rather than a state revealed by abandoning individuality, and consequently it is a state that has become and therefore it is a state which will come to an end.
Said another way the pure mind is held to be a possession of the individual by the Zen/Mahayanist, whereas here the pure mind is obstructed by individuality.
One can see the difference in the thinking of the two if one looks at the behavior of the individuals. The Zen/Mahayanist sees no conflict with Awakening in breaches of morality, self-control or holding on to ideas of existence and non-existence whereas Gotama's emphasis on training in these areas reflects the fact that it is with breaches of morality and self control that points of view manifest themselves as individualities.