A thrown ball follows the same parabola regardless of who catches it. Shannon (1980) put the constraints that govern that parabola into a single equation - flight time, dwell time, hands, balls per hand. None of the variables describe the body of the person catching. The arc is physics. Adaptation happens at the receiver.
This is the argument against most prerequisites in technical learning. The pattern works across a range of bodies, postures, and starting points that the standard teaching has rarely tested.
What the arc is
The arc is a juggling prop’s path - the trajectory of something thrown, passed, received. The path does not belong to one way of moving. The arc is physics. The person receiving it adapts.
This is the argument against prerequisites in learning.
Prerequisites are claims that the arc only reaches certain people. That before you can learn to catch, you need to learn to stand a particular way. That before you can receive the throw, you need to have a certain background. These are usually wrong. They are descriptions of how the skill was previously taught, not descriptions of what the skill requires.
Learning as adaptation, not uniformity
A leaping dancer, a seated practitioner, and a person in a wheelchair are not doing the same thing. Each does what their body allows and what their attention chooses, and the arc connects them anyway.
For some learners, that means examples first, then concepts. For others, the opposite. The goal is not identical approach - it is that the arc reaches each person in a form they can receive and use.
This is how effective teaching of technical skills actually works. The goal is not for every learner to approach the subject identically. The goal is for the arc - the core insight, the transferable technique, the working mental model - to reach each person in a form they can receive and use.
Different positions are not different levels
The dancer’s leap is not more valuable than the seated concentration. A wheelchair does not place a practitioner at the edge of a community in the sense that matters - it is just a different posture from which to receive the arc.
Each is a node in the same pattern, and the arc is equally present at each one.
What “no prerequisites” requires
Saying there are no prerequisites and meaning it requires something more than removing the formal requirement.
It requires that the material actually be accessible at the point of entry - not accessible in a watered-down way, but accessible in a way that allows a genuine start. The arc has to be reachable from wherever the learner is standing. Or sitting. Or leaping.
It requires that early questions be treated as good questions - because they are. A question that reveals an assumption the material makes without stating it is more valuable than a question about an advanced edge case, because it points to a place where the arc could reach more people but currently does not.
The arc as shared infrastructure
In a passing pattern the arc does not belong to any one juggler. It passes through everyone in the pattern. If any one of them drops their end, the arc breaks - not just for them, but for everyone connected to them.
This is what a learning community is, at its best: a structure where the knowledge does not live in one place or with one person, where many different people are holding different parts of the arc, and where the shape of the arc is maintained by the participation of everyone who is part of it.
The arc reaches everyone who is willing to hold it. That is the only requirement.
Reference: Shannon, C. E. (1980/1993). “Scientific Aspects of Juggling.” In Sloane and Wyner (eds.), Claude Elwood Shannon: Collected Papers. IEEE Press. The juggling theorem and its variables - none of which describe the body of the catcher.
Read next: Everyone Juggles - why the cascade pattern has no body-type prerequisite.