• Unity: Every element in a room should relate to other elements in the room in some way. They may have color or texture in common or the lines of the furniture are in harmony, where the parts feel like they belong together. Harmony and rhythm are closely related and form unity.
• Harmony describes unity of mood and is achieved by using pieces that share the same Elements of Design. Repetition creates harmony as with patterns, colors or lines.
• Rhythm is the repetition of pieces and relates to the tempo at which your eye moves around a room. This visual rhythm is akin to the auditory percussion in music. Rhythm and harmony are closely related - where as harmony uses pieces that share the same
Elements of Design, rhythm uses the repetition of those pieces. Alternating contrasting pieces in size or color creates a dynamic rhythm. For example, one could alternate unlit candles of two different colors in a row across a windowsill or fireplace mantle. Progression, or gradation rhythm, sets a tempo through a series of progressively larger shapes. Examples of this can be found in kitchen canister sets or in a small-to-large vase series. Use progression in small amounts or it'll look contrived.

To illustrate this, if there was a room of furniture with clean, straight lines, the addition of a curvilinear sculpture, would favorably contrast the clean lines of the furniture. This would be an excellent backdrop for the sculpture's curvy complexity. Balance is key with this or any other element.