Gregory the Great

O that ye would altogether hold your peace, and ye should be accounted wise!

As in a house, when the door is shut, it is not known what members there are hidden within, so, generally speaking, if a fool hold his peace, it is hidden whether he be wise or foolish, only, however, if no other works come to light, which may speak the mind even of one that is silent. For this reason the holy man, seeing that his friends were anxious to appear what they were not, charged them to hold their peace, that they might not appear what they were. And hence it is said by Solomon; Even a fool when he holdeth his peace is counted wise. But because when a fool speaks, from this, that he brings in his own words, he is unable to reflect on the words of the wise, after he had bidden silence, he yet further adds lightly.