Arslanian blindfolded in the tunnel
It’s the same sort of block some people get with the Mean-Value Theorem. Or in Optics when we get to color fields. At a certain level of abstraction it’s like the brain recoils.
Context
First half of the E.T.A. Optics-curriculum cluster: Pemulis, diagnosing Doucette's conceptual block over annulation, reaches for Optics as the standard example of where E.T.A. brains recoil — Optics is just there in the academy's course sequence, capitalized, a subject with a known hard part (color fields), taught to tennis prodigies because the Founder built the school out of an optics career. The second half lands two pages later, Pemulis selling Arslanian the right-triangle model: "you’ll tapdance right through Watson’s kiddie-physics and up into Optics, which is where the abstracto-conceptual fur really flies, kid, let me tell you" (pp. 571-572). Between them the curriculum is mapped: kiddie-physics below, Optics above, the dead filmmaker's discipline still the summit of the E.T.A. science track. Cross-refs: the roster carries the curriculum's apparatus side at 053 (JOI's lenses/labs used in E.T.A. teaching) and 129's tunnel "Optics I & II lab reports".