Why does every clasp assembly need a rest on the abutment tooth? The clasp's job is retention (resisting lift-off), but chewing drives the denture downward. Without a rest seated on a prepared tooth surface, the denture would sink into the gum tissue under load, traumatizing it. The rest transfers occlusal forces along the tooth's long axis — the direction teeth tolerate best — protecting both tooth and tissue. Retention without support injures; the curriculum pairs them inseparably.