Alexander Calder was the guy who invented the mobile. This comes as a shock to me, who grew up with a mobile above my head (birds of the West, including the glorious California Condor). I always assumed the mobile was a form that had existed since the dawn of time, while being extremely cool. Yet, I was always wrong: a fabulously inventive man invented it once.
The birds of the West mobile broke and lay discarded in my closet for years. Last summer, in an attempt to reclaim the kind virtues that I buried in middle school, I took out the mobile and found that it was twisted in a variety of knots and that the wires had snapped in a few places. After hours of tedious work, I fixed it.
I recommend fixing a mobile if you ever want to understand perfect balance.
I'm a rebellious dude, and I rebel particularly against perfect balance. In static sculpture or static painting, I find perfect balance perfectly boring. Yet a mobile is a way for me to tap into this design principle and really appreciate it.
I realize balance is not, in fact, object staying put. It is objects being pulled apart in perfect opposition to each other, like vectors whose sum is 0. Balance is the potential for an object to break apart in any number of ways, and in this it is even more dynamic than inbalance, which falls apart in only one way.
Here is a pretty mobile of Calder's, made rather late in life: 1960, when he was 62 years old.