|Keiko Goke, My Double Wedding Ring, 2008; 88"x87" (via)|
The yellow centres tie it all together (their shape helps too); they look to be slightly different shades of yellow... and then you notice the red squares, another shape contributing to the lively mix and harmonious variety, and the colour contributing to that variety too. The dark yellow finds its way among the reds and oranges, and one of those squares is definitely a rectangle - though another rectangle is made by two reds of similar tonality.
As you notice (and verbalise) what's going on, you find yourself looking and looking...
Keiko Goke also designs fabric, a wide range including this one -