[Draftcasino.com]

What is understanding?

It is understanding (panna) in the sense of act of understanding (pajanana). What is this act of understanding?

It is knowing (janana) in a particular mode separate from the modes of perceiving (sanjanana) and cognising (vijanana).

For though the state of knowing (janana-bhava) is equally present in perception (sanna) , in consciousness (vinnana) and in understanding (panna), nevertheless, perception is only the mere perceiving of an object as, say, 'blue' or 'yellow'; it cannot bring about the penetration of its characteristics as impermanent, painful and not-self.

Consciousness knows the object as blue or yellow and it brings about the penetrating of its characteristics, but it cannot bring about, by endeavouring, the manifestation of the [supramundane] path.

Understanding knows the object in a way already stated, it brings about the penetration of the characteristics and it brings about, by endeavouring, the manifestation of the path.

Suppose there were three people, a child without discretion, a villager and a money changer, who saw a heap coins lying on a money changer's counter.

The child without discretion knows merely the coins are figured and ornamented, long, square or round; he does not know that they are reckoned as valuable for human use and enjoyment.

And the villager knows they figured and ornamented, etc, and that they are reckoned for human enjoyment; but he does not know such distinctions as "this one is genuine, this is false, this is half value'.

The money changer knows all those kinds and he does so by looking at the coin and by listening to the sound of it when struck and by smelling its smell, tasting its taste and weighing it in his hand and he knows it was made in a certain village or town or city or on a certain mountain or by the banks of a certain river and that is was made by a certain master.

And this may be understood as an illustration.

Perception is like a child without discretion see the coin because it apprehends the mere mode of appearance of the object as blue and so on.

Consciousness is like the villager seeing the coin because it apprehends the mode of the object as blue, etc, and because it reaches further, reaching the penetration of its characteristics.

Understanding is like the money changer seeing the coin because after apprehending the mode of the object as blue, etc, and extending to the penetration of the characteristics, it extends still further, reaching the manifestation of the path.

This is why this act of understanding should be understood as 'knowing in a particular mode separate from the modes of perceiving and cognising'.

For that is what the words 'it is understanding in the sense of act of understanding' refer to.

XIV, 3 - 5