When discussing the principles of Unity, Harmony and Variety, it is almost impossible to describe one without talking about the other two. Unity is the repetition of a common element or characteristic within your space to provide visual harmony. For example, a monochromatic color scheme or repetition of shape and form within a design brings sameness and cohesion.
Now in order to avoid dull-ness and keep designs interesting, designers introduce “pops” of variety to their designs adding to the unity of the space. We add variety to balance out the harmony and vice versa.
To avoid the chaotic, disorganization of too many dissimilar elements, you can add to their harmony by grouping them together as seen in the photo above. By taking a variety of miss matched side chairs, you can add harmony to the group by painting them a unified color.