Neither do men put new wine into old bottles: else the bottles break, and the wine runneth out, and the bottles perish: but they put new wine into new bottles, and both are preserved. New wine into old bottles - It is still the custom, in the eastern countries, to make their bottles of goat skins: if these happened to be old, and new wine were put into them, the violence of the fermentation must necessarily burst them; and therefore newly made bottles were employed for the purpose of putting that wine in which had not yet gone through its state of fermentation. The institutes of Christ, and those of the Pharisees, could never be brought to accord: an attempt to combine the two systems would be as absurd as it would be destructive. The old covenant made way for the new, which was its completion and its end; but with that old covenant the new cannot be incorporated.
Christian prudence requires that the weak, and newly converted, should be managed with care and tenderness. To impose such duties and mortifications as are not absolutely necessary to salvation, before God has properly prepared the heart by his grace for them, is a conduct as absurd and ruinous as putting a piece of raw, unscoured cloth on an old garment; it is, in a word, requiring the person to do the work of a man, while as yet he is but a little child. Preachers of the Gospel, and especially those who are instruments in God's hand of many conversions, have need of much heavenly wisdom, that they may know to watch over, guide, and advise those who are brought to a sense of their sin and danger. How many auspicious beginnings have been ruined by men's proceeding too hastily, endeavoring to make their own designs take place, and to have the honor of that success themselves which is due only to God.