While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?

As the process of dissolving an acid or a base in water is a highly exothermic one so the acid must always be added slowly to water with constant stirring. If water is added to a conc. acid, the large amount of heat generated may cause the mixture to splash out and cause burns. The glass container may also break due to excessive local heating.