#30 - A Case of Conscience by James Blish

[Geoff]

The citizens of the planet Lithia are some of the most ethical sentient beings Father Ramon Ruiz-Sanchez has ever encountered. True, they have no literature, no fine arts, and don't understand the concept of recreation, but neither do they understand the concepts of greed, envy, lust, or any of the sins and vices that plague humankind. Their world seems darned near perfect. And that is just what disturbs the good Father.