You bear a name to which you answer. But your body was not born with that name written on it, nor did it say to anyone that it bore such and such a name. And yet a name is given to you and you answer to that name, because you have identified yourself with the name. Therefore the name signified something and it is not a mere fiction. Similiarly, God's name is effective. Repetition of the name is rememberance of what it signifies. Hence its merit.