2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/57731I describe how my involvement with monopoles related to the multimonopole existence proof of Taubes, and how my later work on quaternionic quantum mechanics led to the classification theorem for generalized projective group representations of Tao and Millard.8 pages; for a volume on the influence of Yang-Mills theory on mathematics, G. 't Hooft and W. Nahm, eds., to be published by World Scientific. Final version; references addedMathematical PhysicsHigh Energy Physics - TheoryHistory and Philosophy of Physicstext