The article examines Wittgenstein's thought on the language of pain in first and third person. Relevant grammatical differences, according to the typical analytical method of this philosopher, are highlighted not only in relation to the two perspectives, but also regarding the use of cognitive verbs such as 'feeling' and 'knowing'. The exam of many texts suggests some issues concerning the relationship between personal experiences, empathic grasping of other's feelings and their conceptual translation. A brief comparison with some Thomas Aquinas' texts complements the proposal of the existence of non intentional knowledge.