The Co to the Mahaaraahulovaadasutta refers to the Visuddhimagga that
comments on the Anapanasati sutta. After having quoted the Commentary to the
first, second and third Tetrad, I shall now continue:
The fourth Tetrad, dealing with the Contemplation on Dhammas, Mental
Objects.
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We read in the Commentary to the Anapanasati Sutta (translated by Ven.
Nyanatiloka) about the explanations of the words of the sutta:
<Having seen with understanding the abandoning of covetousness and grief, he
becomes one who looks on with complete equanimity>: here covetousness is the
hindrance of lust. By grief the hindrance of ill will is pointed out. For
this tetrad is stated by way of insight. And contemplation of mental objects
is sixfold... Of that contemplation, the section on the hindrances is the
beginning... Accordingly, he said, <covetousness and grief> in order to
point out the beginning of the contemplation of mental objects. <The
abandoning> (pahaana.m) means it is the knowledge of abandoning, thus, <he
abandons the perception of permanence through the contemplation of
impermanence> that is intended...
N: The Co refers to higher stages of insight knowledge leading to more
detachment from conditioned realities: fading away (viraaga~naa.na),
cessation (nirodha ~naa.na), and relinquishment (pa.tinissagga). We read
further on:
<That is why... bhikkhus>: because one who proceeds by the method,
<contemplating impemanence, I shall breathe in,>etc., is one who looks on
with complete equanimity after successively seeing with understanding not
only the mental objects beginning with the hindrances, but also the
knowledge of the abandoning of the mental objects stated under the heading
of covetousness and grief. Therefore, it should be understood that <on that
occasion... a bhikkhu abides contemplating mental objects in the mental
objects.>

Nina: In the Way of Mindfulness, Co translated by Ven. Soma, it is stated
that just as in the case of body, feeling and citta, the mental objects
should be contemplated in seven ways: as impermanent; as being subject to
dukkha; as anatta; by way of turning away from it and not by way of
delighting in it; by freeing himself of passion for it; with thoughts making
for cessation and not making for origination; and not by way of laying hold
of it, by by way of giving it up.
As we have seen, the hindrances are classified under the mental objects, and
they include also the khandhas, the sense-bases (ayatanas), the seven
factors of enlightenment and the four Truths.
(to be continued)
Nina.