Wherever there is a main issue the elimination of other things which are not essential will make for a stronger result. In the earlier static abstrac… - Alexander Calder

Therefore, why not plastic forms in motion? Not a simple translatory or rotary motion but several motions of different types, speeds and amplitudes composing to make a resultant whole. Just as one can compose colors, or forms, so one can compose motions.

Question: How do you get that subtle balance in your work?
You put a disk here and then you put another disk that is a triangle at the other end and then you balance them on your finger and keep on adding. I don't use rectangles - they stop. You can use them; I have at times, but only when I want to block, to constipate movement.

The two motor driven "mobiles" which I am exhibiting [August, 1933] are from among the more successful of my earliest attempts at plastic objects in motion. The orbits are all circular arcs or circles. The supports have been painted to disappear against a white background to leave nothing but the moving elements, their forms and colors, and their orbits, speeds and accelerations.