No man puts a piece of new cloth onto an old garment, for that which is put on to fill it up takes from the garment, and the tear is made worse.
All Commentaries on Matthew 9:16 Go To Matthew 9
George Leo Haydock
A piece of raw cloth. By the Greek is signified new-woven cloth, that has not yet passed the hands of the fuller. (Witham)
And no one putteth Christ, by these similitudes, justifies the manner of life which he taught his disciples, which at first was adapted to their understandings; lest, if in the beginning, he had required them to fast contrary to what they had been accustomed, they might have been frightened at the austerity of his institute, and deserted him. He compares, therefore, his disciples to an old garment, and to old bottles; and an austere mode of life to new clothes and new wine. And he argues, that if we do not put new cloth to an old garment, because it tears the garment the more, nor put new wine into old bottles, because by its fermentation it would easily break them, so in like manner his disciples, who had been accustomed to a less rigid mode of life, were not at once to be initiated into an austere discipline, lest they should sink under the difficulty, and relinquish the pursuit of a more perfect life. (Menochius)