I don’t think that was what he was saying. Perhaps he was saying that price, in terms of money, is the nominal portion of the exchange. You are exchanging value for value in a barter situation, so if money is used as a medium of exchange then it has some sort of value. In fact it has the value, to the person giving the money, less than that of the good being received. To the giver of the good, the money has a greater value than that of the good being given up.