Trees of virtues were a metaphorical method employed by medieval Christian monks to assess the relationships between virtues. In a tree of virtues, some virtues are designated as the most heavenly while other virtues are considered aspects, or branches, of those virtues. These "secondary virtues" were considered less directly associated with heaven.
Trees of vices were analogous metaphors used to determine the relationships between sins. While on a tree of virtues, the leaves point upward toward heaven, on a tree of vices the leaves point downward toward hell.