John Calvin on John 20:30

30. Many other signs also Jesus did. If the Evangelist had not cautioned his readers by this observation, they might have supposed that he had left out none of the miracles which Christ had performed, and had given a full and complete account of all that happened. John, therefore, testifies, first, that he has only related some things out of a large number; not that the others were unworthy of being recorded, but because these were sufficient to edify faith. And yet it does not follow that they were performed in vain, for they profited that age. Secondly, though at the present day we have not a minute knowledge of them, still we must not suppose it to be of little importance for us to know that the Gospel was sealed by a vast number of miracles.