Serenity of mind, gentleness, silence, control of the Self, and purity of the emotional being — that is said to be the austerity of the mind.

Mental tapas (mānasam). Manas-prasādaḥ — serenity/clarity of mind. Saumyatva — gentleness, radiantly calm (saumya = lunar, serene). Mauna — internal/external silence, not merely absence of words but of incessant thought.

Ātma-vinigrahaḥ — control of the Self, dominion over the psychic instrument. Bhāva-saṃśuddhi — purification of emotions/internal foundations. These are the disciplines of the inner world.