2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/48639A brief introduction is given to the methods and spirit of effective lagrangians. The emphasis is on a summary of the overall picture, using a simple model as the vehicle to motivate and illustrate the main points. Powercounting is illustrated by estimating the size of the quantum corrections to the predictions of classical gravity.18 pages, LaTeX, no figures. Invited talk presented to RADCOR 98, Barcelona, September 1998High Energy Physics - PhenomenologyCondensed MatterGeneral Relativity and Quantum CosmologyHigh Energy Physics - TheoryNuclear Theorytext