Each person is unique and needed as he is and must live his life. Inside each person there is a whole Universe in which there is everything: dark and light, love and antipathy, destruction and creation, pain and pleasure, fear and courage. Harmony is not just one thing. Harmony is the coordination of heterogeneous and even opposite (conflict) elements.
It is impossible to realize outside what is not inside. If there is no harmony within oneself, but only denial, no acceptance, no consent, aggression. In the outer life it will all be the same. That is a violation of the balance between spirit and matter.
If you want harmony then start by knowing yourself, then accept yourself as you know yourself, with all your best and worst qualities.