It used to be the practice that before asking a Rebbe for a Bracha one would give him a small amount of money, called a pidyon.
A gift affects ones Neshama and bends ones heart to the giver, as well as increasing Simcha. This is why Yaakov Avinu asked Esav to hunt some delicacies for him before giving him the Bracha.
Ones heart, everyones, is bent by a payment, this is thoroughly discussed, regarding bribes, in many sugyas in the Gemorrah. It is a universal component of human nature.