Ayah 1-4: Man's activities can be both good and bad, with different rewards and punishments.
Ayah 5-11: Self-purification can be achieved through sincerely spending in Allah's way.
Ayah 12-21: The successful are friends of Allah and people, generous, and fear God. The unsuccessful are enemies of Allah and people, stingy, and deny truth. For the successful, goodness is easy while evil is difficult. For the unsuccessful, evil is easy while goodness is difficult.