Answer

The Acharanga Sutra is one of the most important Jain Agams, especially in the Śvetāmbara tradition. It mainly teaches the conduct of Jain monks, the discipline of non-violence, self-control, carefulness, and renunciation.

However, in the commonly accepted Śvetāmbara Jain Agam classification, the Acharanga Sutra is generally divided into two Śrutaskandhas — not usually referred to as a “3rd book.”

So, if by “3rd book” you mean a specific chapter, section, or a modern printed volume division, please share the exact title or first few words, and I can explain it more accurately.

Explanation

The Acharanga Sutra focuses on:

• Ahimsa — absolute care to avoid harming living beings.
• Monastic discipline — how a sadhu should walk, speak, eat, rest, and behave.
• Renunciation — giving up attachment to body, possessions, comfort, and ego.
• Awareness of living beings — sensitivity toward even subtle forms of life.
• Life and conduct of Bhagwan Mahavir — especially his hardships, equanimity, and spiritual endurance.

The text teaches that a true seeker must live with extreme alertness, compassion, restraint, and inner purity.

Spiritual Understanding

The central message of the Acharanga Sutra is that non-violence is not only an outer action but a complete way of living. A monk must avoid violence by body, speech, and mind, and must remain detached even in pain, insult, hunger, heat, cold, or discomfort.

It shows the depth of Jain Dharma: liberation is approached through careful conduct, self-discipline, and complete freedom from attachment and aversion.

Takeaway

The Acharanga Sutra teaches that spiritual life begins with carefulness, compassion, and self-restraint. If you meant a particular “third book” section or chapter, please share its name, and I can give a more focused overview.