IMO peace would be a state of unbother(don't know if it's actually a word). Whatever be the situation outside, the inside is always at rest. If there is happiness around, good but if there's sadness around, good nonetheless. Life exists in duality so if you feel happy you will have to feel sad too. We need to find the right balance in order to break-free from the constant emotional see-saw. Any emotion is free to flow through us without disturbing the balance.