To learn how to juggle, you have to learn first how to let the balls drop.
Calibrating the sound as they hit the ground one after the other. Hearing how the spaces between the drops start getting equal. Noticing the arches made by your throws. Appreciating how they firm up and become consistent.
Throw, throw, throw. Plop. Plop. Plop. Again.
The sound, the noticing of the patterns, and letting go of the urge to catch.
These are the systemic observations that let a single ball flow elegantly through the air.