Bhagavad Gita Bhasya (Gambhirananada)

one's behaving like lunatics or drunkards. [A
lunatic is one who has lost his power of
discrimination, and a drunkard is one who has that
power but ignores it.] Hence it is said: Tustah,
remains satisfied; atmani eva, in the Self alone, in
the very nature of the inmost Self; atmana, by the
Self which is his own -- indifferent to external
gains, and satiated with everything else on account
of having attained the nector of realization of the
supreme Goal; tada, then; ucyate, he is called;
sthita-prajnah, a man of steady wisdom, a man of
realization, one whose wisdom, arising from the
discrimination between the Self and the not-Self, is
stable. The idea is that the man of steady wisdom is
a monk, who has renounced the desire for
progeny, wealth and the worlds, and who delights
in the Self and disports in the Self.
2.56 That monk is called a man of steady wisdom
when his mind is unperturbed in sorrow, he is free
from longing for delights, and has gone beyond
attachment, fear and anger.
English Translation of Sri Sankaracharya's Sanskrit
Commentary - Swami Gambhirananda
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