To borrow the form of Pilate's well-known question about truth and ask, "What is peace?" would probably elicit a reply indicating that peace is regarded as the absence of war. Yet that is no more pertinent than it would be to say that light is the absence of darkness, or good the absence of evil.
General belief regards light as positive, and darkness as merely the absence of light. No one can make a light room dark except by shutting out the light. So peace may be regarded as the positive and war as belief in the absence of peace.
Christian Science insists that since God is the only cause there can be no effect from any other cause, and that, since like produces like, good, peace, harmony, are positive conditions of being, while evil, war, inharmony are negative, without a real cause.