Yitzchak possessed three unique qualities of "of being firsts" that Avraham never experienced. Yitzchak was the first person born as a Yid. Secondly, he was the first Yid who had his Bris Milah at eight days old. Being the first Yid born in the world deserved a special simcha and joy and that is why he was called Yitzchak which means happiness. However, being born Jewish has its incompletion as well. This we can see from the Beracha that our Chachamim established for us to recite every morning .שלא עשני גוי Commentators ask why thank Hashem for not giving you the identity of being born a goy when the beracha should rather state thank you Hashem for creating me a Yehudi. They answer that life is not about being born a Yid but rather living up to the name Yisrael which is a life's dedication of striving to live up to the standards of serving Hashem founded by our Avos and Imahos. This mission statement is alluded to in the acronym of ישראל which represent אברהם יצחק יעקב שרה רבקה רחל לאה. Who could say that they have definitely achieved this goal? Therefore our Chachamim preferred to say thank you Hashem for not making me into a goy which is a certainty.
Avraham even though he wasn't born a Yid he was the first Yisrael, an accomplishment which he achieved with tremendous toil and mesiras nefesh passing all Ten Tests with which Hashem challenged him. His name was changed with an added ה adding up to 248 corresponding to the 248 limbs that he sanctified to Hashem through his dedicating them to daily avodas Hashem. By doing so it was deemed as if he gave birth to himself and instead of physically being born from Terach the idolater, he was born from himself as a Yisrael with all of its madraigos. This is why the Osherever Rebbe ztl says Avraham was called an Av because his transformation of his original self was so supernatural that it was considered as if he fathered himself a"k.
This is what Hashem meant when he told Avraham לך לך go to yourself and become as if you gave birth to yourself. By doing so you will purify yourself from all the לכלוך impure influences such as your father, birthplace, and country (the two above words share the same letters). The gematria of לך is הולדה giving birth the journey of self - creativity. This is the madraiga that you can attain by cleaving to me over your father.
In contrast to his father, Yitzchak was born from the towering giant of spirit Avraham. Unlike his father he did not have to go through Ten Tests in order to be reborn a Yid for he possessed a great head start. Yet in Yitzchak's name is hinted Ten Tests as Rashi brings the Chazal (17,21) that the acronym of יצחק is the letter yud which corresponds to the Ten Tests (of Avraham), the letter tzadi correlates to the age of Sarah when she gave birth to him 90, the ches of Yitzchak represents the eight day of Milah is which Yitzchak was eight days old, and the letter kuf symbolizes that Avraham was one hundred years old when Yitzchak was born.
Why then is the letter yud in Yitzchak related to Yitzchak when it was Avraham's Ten Tests and not at all associated with Yitzchak's birth as the other letters hint to? We suggest the answer is that Yitzchak had two births. One was from Avraham and the other from Hashem. The tachlis of the Ten Tests was the last and ultimate test, the Akaida. Chazal say that Yitzchak's neshama at the Akaidah departed from him and he experienced the first human Techiyas Hamaisim when Hashem returned his neshama. That is why we find that the second beracha of Shemoneh Esrai is Yitzchak's beracha which mentions Techiyas Hamaisim five times. Chazal also say that that the key to Techiyas Hamaisim is only in the hands of Hashem (Taanis 2). Therefore in essence Yitzchak was born again with Hashem as his "Father" at the Akaidah. With this explanation the letter yud of Yitzchak now also relates to his birth for it is referring to his second birth at the climax of the Ten Tests of Avraham Avinu. This is fact lists also the third "innovation" that Yitzchak achieved over Avraham Techiyas Hamaisim.
We suggest that this interpretation is alluded to in the promise of Hashem to Avraham כי ביצחק יקרא לך זרע (Bereishis 21,12) Chazal ask why Hashem added an extra letter ב to Yitzchak? It would have been sufficient just to say כי יצחק יקרא לך זרע excluding Yishmael. We can say that the extra ב is to relate to us that there are two Yitzchaks, one born from Avraham and a second reborn through Techiyas Hamaisim. Hashem is telling Avraham that from Yitzchak number one or number two only Yitzchak will be called your זרע seed. One might have thought that since the first neshama of Yitzchak left him and Hashem gave him a new neshama (see Ohr Chaim 22,20) maybe he would lose his identity of being called Avraham's zerah. It was therefore that Hashem added the ב in order to clarify that nevertheless even the second Yitzchak is still considered to be the only zera of Avraham.
Why was this tenth test of Avraham called עקדה which only conveys the preparation to the sacrifice and not the actual korban? Sometimes one can find himself in a life threatening crisis and there seems to be no way that one can escape his unfortunate fate. Yet Chazal state Berachos 10
מקובלני מבית אבי אבא אפילו חרב חדה מונחת על צוארו של אדם אל ימנע עצמו מן הרחמים אתמר נמי רבי יוחנן ורבי (אליעזר) [אלעזר] דאמרי תרוייהו אפילו חרב חדה מונחת על צוארו של אדם אל ימנע עצמו מן הרחמים
That even if one finds himself in the scenario that a sharp sword is laying on one's neck and he is about to be killed, but nevertheless he should not give up from salvation but rather still ask for compassion from Hashem. Yitzchak was tied legs to hands with no way of avoidance and yet he was saved at the last second when the knife was already on his neck.
Recently we witnessed Hashem's tremendous display of rachamim with the plane episode from Dubai which suddenly turned into an imminent death sentence to all 174 passengers. As the plane nose - dived without a pilot, it was as if all their bodies were tied on an altar of sacrifice totally helpless to avert the malach hamaves who was staring at them right in their faces. Yet with a minimum of at least Ten miracles which Hashem sent and planned ahead of time, all were saved, the passengers and the plane. For those 174 passengers they also experienced their personal Akaidah. Their relationship with Hashem hopefully will improve somewhat to at least be better than it was before experiencing the Hand of Hashem upon them. Would you say it is merely a coincidence that the 174 passengers is gematriah עקד? I definitely don't think so. Like Yitzchak they were given a second lease on life tantamount to Techiyas Hameisim.