Harmony attracted mankind since ancient times. The world is whole, diverse, and committed to excellence, and that is harmony. Harmony is associated with such concepts as: development, organization, and structure. However, in the heyday of industrialization, harmony faded, as speed and optimization came out on top. Breach of proportion and consistency led mankind to a distortion of reality and confrontation with Nature. In this work the attempt is made to revive the concept of harmony in the broadest sense: art, creativity, economics, and ecology. One of the major problems of harmony is its measurement. In this paper, as a measure of harmony is used the ratio of chaos and order, as measured by the relative entropy. A significant quality of harmony is its link with the process of self-organization, which is especially important in creation and development of democracy and civil society. In this regard, a lot of attention in this work is paid to social processes. As a result, the author intends to show that the principles of harmony are the essential components of modern philosophy and development.