fountain - an image of the heart: as the aperture (so the Greek for “place” is literally) of the fountain is an image of man’s mouth. The image here is appropriate to the scene of the Epistle, Palestine, wherein salt and bitter springs are found. Though “sweet” springs are sometimes found near, yet “sweet and bitter” (water) do not flow “at the same place” (aperture). Grace can make the same mouth that “sent forth the bitter” once, send forth the sweet for the time to come: as the wood (typical of Christ’s cross) changed Marah’s bitter water into sweet.