I heard that once, on a flight, Srila Prabhupada was talking to the plane’s pilot, a man Srila Prabhupada described as “intelligent.” He asked Srila Prabhupada how he — a man of God — explained the existence of evil. Srila Prabhupada said, in essence, that when flying westward one “chases the sun,” and daylight is prolonged. When travelling eastward one experiences early darkness. When one faces the sun, one faces goodness, when one faces away from the sun, one looks at evil. It’s a matter of attitude. The sun can be compared to God. Darkness is also caused indirectly by the sun (due to it being obscured), and therefore evil may be construed as the “backside of God.” Srila Prabhupada indicated that the pilot understood and appreciated this explanation.