Oliver Cowdery stated that the plates were "translated by the gift and power of God."
Oliver Cowdery, “Letter VIII,” Messenger and Advocate 2, no. 1 (October 1835): 198
[T]hey cannot be interpreted by the learning of this generation; consequently, they would be considered of no worth, only as precious metal. Therefore, remember, that they are to be translated by the gift and power of God. By them will the Lord work a great and a marvelous work