Baal Shem Tov(Parshas Noach): When the guest sees that the father gets pleasure from this activity and the guest wants the father to have more pleasure – he challenges the son further. He asks more questions which are even stronger and involve new issues. The son responds to the challenge and answers all the questions. This is what is meant that whoever is greater than his fellow he has a greater yetzer. Our Sages (Bava Basra 16a) say that Satan works for the sake of Heaven. The parable is obvious that when the tzadik controls the yetzer harah, G‑d receives pleasure from it. The yetzer harah responds by offering increasingly greater challenges - to which the tzadik responds by defeating it. This is the meaning of Megila (18a) that G‑d called Yaakov “ail” (a divinity). The term “ail” is a language of strength and might (Yevamos 21a). … This is also why a tzadik is called a gibor (hero) in that he conquers his yetzer (Avos 4:1). And in the future the tzadikim will see that their yetzer harah is like a mountain (Sukka 52a). At that point the power of the tzadikim will be obvious to all since they have conquered this great mountain. It is also possible that in the future that everyone will call tzadikim “ail".