Who doesn't want a peaceful mind? Most religions and wisdom philosophies seek peace. Christ is the Prince of peace. Peace is shalom and salaam, preferred greetings in Judaism and Islam. Shanti, peace, is a Hindu prayer. Buddhists equate peaceful mind with Nirvana.
Peaceful mind is mental and emotional calm, happiness and clarity, unconditioned by the events around us and our own feelings and thoughts. Peaceful mind is expansive, limitless, crystal clear, kind and compassionate. Perhaps you have experienced it for yourself. That sense of everything being alright just as it is.