Our Sages compare charity and one's wealth to salt and meat. When people needed to preserve their meat they would need to place it in a bit of salt, not a lot of salt, but a certain amount. So too, a person needs to give a certain amount of charity in order to preserve their "meat" wealth. They tell of a young woman whose father and father-in-law were two of the richest Jewish men in the time of the destruction of the Second Temple. She was found utterly destitute and when they asked what happened to all of her families money  she told them that their money was lost because they didn't give charity properly.