Musar zu Daniel 10:20

Nachmanides (Chavell edition page 158), describes the meaning of the dream according to Rabbi Eliezer the Great as follows: This vision is similar to the vision Abraham experienced at the ברית בין הבתרים (Genesis 15), where G–d showed Abraham the four kingdoms who would rule over Israel in exile. The rise and fall of these empires is compared to angels ascending and descending the ladder. The reason they are called "angels of G–d," is similar to Daniel 10,20 where the angel Gabriel describes himself as ready to do battle with the angels described as שר מלכות יון, and as שר מלכות פרס respectively. G–d promised that He would be with Jacob (people of Israel) in all his sojourns with them, would protect and save him from those empires. G–d showed Jacob how these four empires would rise and subsequently fall. He also showed him that the angel representing Babylon would rise to a height of seventy rungs on the ladder before descending, (seventy years' exile), whereas the angel representing the kingdom of the Medes would ascend one hundred and eighty rungs before descending. When shown the angel representing the kingdom of Edom ascending and not descending, Jacob asked G–d to hurl him down into the grave. G–d responded that even if he, Edom, were to climb sky-high, He would bring him down (Ovadiah 1,4).

What all this has to do with Samael injuring the כף ירך יעקב, the thigh joint of Jacob, is simple. Our sages say on 32,26: וירא כי לא יוכל לו, ויגע בכף ירכו ותקע כך ירך יעקב, that the thigh joint of Jacob refers to the later descendants who experienced the harsh decrees by the various nations who were their hosts in exile. When the Hasmoneans overcame the Greeks, they reversed this injury, i.e. the כף became a פך a cruse of oil. What had been a vulnerable part of Jacob's ירך now became the solid basis of the candelabra, ירך מנורה.