The Travelers and the Plane Tree

Some travelers, on a hot day in summer, oppressed with the noontide sun, perceiving a plane tree near at hand, made straight for it. Throwing themselves on the ground, they rested under its shade. Looking up towards the tree, they said one to another, "What a useless tree to man is this barren plane!" But the plane tree answered them, "Ungrateful creatures! At the very moment that you are enjoying benefit from me, you rail at me as being good for nothing."

Ingratitude is as blind as it is base.