In Jain dharma, surgery is generally considered physically हिंसक (dravya-hinsa) because some injury to living beings in the body is involved, even if done for treatment.

But for the bondage of karma, bhav-hinsa is the main cause.

Simple Jain understanding:

• Dravya-hinsa = actual harm done to living beings in physical action.
• Bhav-hinsa = harmful intention, inner passion, carelessness, cruelty, or negligence.

So, is surgery harmful to the soul?

• Yes, surgery involves some हिंसा in action.
• But if it is done with a pure motive, without cruelty, greed, anger, or negligence, then the karmic bondage is much less.
• Bhav is very important in Jain ethics. A compassionate medical act done to save life is not the same as violence done out of violence.

Jain view in practice:

• A person may undergo or perform surgery for protection of life, health, and compassion.
• In such cases, the act may still involve some unavoidable हिंसा, but it is not the same as sinful हिंसा done with bad intention.
• The soul is more deeply harmed by sinful inner states like hatred, pride, anger, deceit, greed, and carelessness.

In short:

• Surgery = dravya-hinsa may be present
• Bhav-hinsa = more harmful for the soul
• Pure intention reduces karmic bondage, but does not make physical harm completely absent

If you want, I can also explain this in terms of ārambh, samārambh, and himsā in Jain ethics.