In the Aesop’s Fable, The Ass and His Purchaser, a man looking to buy a donkey wanted to test the animal before completing the purchase. So he put the donkey in his field with the other donkeys to see what would happen.
The donkey immediately strayed from the majority of the herd and cozied up to the laziest donkey of all.
Seeing that, the man led the donkey back to his owner. When the owner asked how he could judge the donkey’s character so quickly the man explained, “I didn’t even need to see how he worked. I knew he would be just like the one he chose to be his friend.” Full Piece