(1) In relation to any event or situation, any statement made by any of the following persons on the occasion or immediately before or after it shall be admitted as evidence:
(a) a person who does the act or who directly sees or knows about the act, event or condition, or
(b) the person who suffered from that act, event or condition.
(2) It shall be taken as evidence that a person expresses his physical or mental condition while maintaining such condition in such a way that it is clearly understood.