2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/92103A complete set of mutually unbiased bases for a Hilbert space of dimension N is analogous in some respects to a certain finite geometric structure, namely, an affine plane. Another kind of quantum measurement, known as a symmetric informationally complete positive-operator-valued measure, is, remarkably, also analogous to an affine plane, but with the roles of points and lines interchanged. In this paper I present these analogies and ask whether they shed any light on the existence or non-existence of such symmetric quantum measurements for a general quantum system with a finite-dimensional state space.18 pages; for a festschrift honoring Asher Peres; minor corrections and added references in v2 and v3Quantum Physicstext