Internal strife is the root of all the machlokes (disputes) in the world. We would go crazy if we were left alone with our internal struggles, so we have disputes with others. All sickness results from machlokes. Aveirah (sinning) imbalances our body. There is no menuchas haNefesh (tranquility) during the week. Disputes increase erev Shabbos (Friday afternoon). Shabbos is a ceasefire from dispute.