If he wishes, he can express his joy by saying ' sadhu' which means ' well done ' . What he is doing is creating a kind of mental or verbal applause. In order to share the good deed done by another, what is important is that there must be actual approval of the deed and joy arising in the beneficiary ' s heart. Even if he so desires, the doer of a good deed cannot prevent another's 'rejoicing in the merit ' because he has no power over another's thoughts. According to the Buddha, in all actions, thought is what really matters.
Transference is primarily an act of the mind.
To transfer merit does not mean that a person is deprived of the merit had originally acquired by his good deed. On the contrary, the very act of 'transference' is a good deed in itself and hence enhances the merit already earned. The Buddha says that the greatest gift one can confer on one's dead ancestors is to perform ' acts of merit ' and to transfer these merits so acquired. He also says that those who give also receive the fruits of their deeds. The Buddha encouraged those who did good deeds such as offering alms to holy men, to transfer the merits which they received to their departed ones.