The Prophet Isaiah had a special talent for suggesting new and sometimes startling ways of looking at things, especially, as in today's reading, ways of looking at our relationship with God and the meaning of certain religious practices. He speaks on behalf of God and criticizes people for carrying out their own pursuits on the days of fasting, and even driving their labourers hard, so that they end up in quarrelling and fasting. He is trying to teach the people that fasting, no matter how religious an act it may be, cannot be an isolated act with no relation to the rest of one's life. He goes on to develop this perspective and suggest that the most genuine practice of fasting will carry with it a wholehearted commitment to justice. In order that the concept of justice may not remain simply a doctrine or a theory, he teaches that justice must express itself in very clear, if very simple, ways. While fasting may take the form of eating less, Isaiah suggests that fasting marked by justice and thus pleasing to God will take the form of "sharing your bread with the poor". In earlier times, the Church systematized such teaching in "the corporal works of mercy" and "the spiritual works of mercy."