There once was a kindly farmer who found a viper freezing on the ground in the snow. Please help me, the poor creature said, for I am too cold to live. The farmer took the viper and put it inside his shirt, and the viper began to warm itself and come alive again. But upon coming alive, it bit the farmer most wretchedly, and as the farmer died, he asked the viper, but why? Why when I was so trusting of you? Because I am a viper, the snake replied. And one cannot expect kindness from evil.

Viper and the Farmer