Rabbi Jonathan Sacks, z/l: Shelach Lecha What Made Joshua and Caleb Different?

Rabbi Sacks writes of the vast discrepancy between the perceptions of the 10 spies and the 2—Caleb and Joshua. He explains the guilt of the former as an attribution error – assuming that others (the Canaanites) saw them as they did themselves—like grasshoppers. They were entitled to see themselves as very small, but not to attribute that to others. Why did Caleb and Joshua not make the same mistake?