Throughout Sefer Bereishit there is great degree of significance associated with names. A name is not merely a way to call someone but, rather, it encapsulates the essence of the individual. Both Avraham and Yaakov received names at birth, yet their names were changed later in life as certain events unfolded. Chazal in Masechet Berachot (13a), draw a distinction between the change in the name of "Avram" to "Avraham" and the change of "Yaakov" to "Yisrael".
Once Avraham received his new name no one was permitted to refer to him by his previous name "Avram", whereas Yaakov is constantly referred to as both "Yaakov" and "Yisrael". Avraham received a new mission, to be "av hamon goyim", a father to many nations, and as such, his previous title, "Av leAram", the father of his own home, is inappropriate. What is it about the name "Yaakov" that it remained alongside "Yisrael"?
The dual name "Yaakov-Yisrael" reflects two aspects of Yaakov's life. He entered the world be hind his brother, grabbing his heel, being stepped on by Esav. The name "Yaakov" is synonymous with all the difficulties he would endure while dealing with his brother. When Yaakov was victorious in his fight with the angel, who chazal interpret to be the Angel of Esav, Yaakov was given a new name, "Yisrael", meaning, one who has overcome his foes. There are times when he was victorious and as such referred to as "Yisrael", yet he endured many hardships, and was constantly reminded that he was also "yaakov".
The most poignant expression of this appears in Bereishit (46:1-2) when Yaakov was traveling to mitzrayim to see Yosef. It was the highpoint of his life, going to greet his son that for 22 years he had thought was dead. The Torah describes the triumphant Yisrael going to Mitzrayim: G-d appeared to him and called him "Yaakov, Yaakov",you are going to galut, your descendants will be enslaved. This is the beginning of a dark chapter in the history of the Jewish people. You may be personally experiencing the emotions of "Yisrael", but be aware that this is the beginning of the period of "Yaakov."
The duality that exists within "Yaakov" repeats itself throughout the history of his descendants. The Sefer haChinuch, in Mitzvah 3 explains that the prohibition of eating the gid hanasheh is symbolic of our entire history. Yaakov is victorious in hid struggle against Esav, but he is wounded in battle.
Esav succeeded in injuring Yaakov's leg even though he could not defeat him. This is true throughout Jewish history. Ultimately the Jewish people will emerge victorious from all of its struggles, but there will be costly sacrifices along the way. We are constantly wounded as a people yet we survive and prosper and will ultimately emerge from exile.
"Maaseh avot siman lebanim," - the lives of the forefathers foreshadow events in the lives of their descendants. Just as Yaakov emerged from his battle with Esav victoriously, so should we merit redemption from our exile , and reach the heights of Yisrael.