When Yitzchak was forty years old, his father found him a wife. The verse describes how Moshe wrote over the Torah at the end of 40 years in the desert. It reads, “Be’are (באר) es a haTorah hazos, he (Moshe) explains the Torah (to the Jews).” The letters of Be’are spell out the acronym beis-bikachto alef-es reish-rivka, “when he (Yitzchak) took Rivkah (in marriage).” Avraham represents the Written Torah (bichsav) and Yitzchak represents the Olal Torah (baal peh). Avraham is kindness, as scripture is referred to as rachmanah, the Merciful One’s (word). Yitzchak was blind, thus he represented the oral Torah which was taught from mouth to ear and passed down orally. He was also din, judgment, which is the Torah shel baal peh aspect, as one needs to toil hard to accomplish an understanding in the Oral Torah. This is why the Jews did not readily accept the Oral Torah at Sinai (see Tosfos, Shabbos 88b and Tanchuma Noach 3).
Just as the Jews waited 40 years in the desert to finally have Moshe explain the Torah shel baal peh to them, mentioned in the verse above, so too Yitzchak waited until he was 40 before taking his wife Rivkah (Sefer Tzioni, quoted by Yalkut Reuveni). There is much content here that needs to be explained.
The Gemara Berachos (6b) says, “anyone who brings joy to a bride and groom merits to learn and succeed in Torah.” This is a nice blessing, but what does it have to do with making a chosson and kallah happy? Shouldn’t you merit your own happiness? The answer is twofold and one in the same. Firstly, success in Torah is your happiness. Secondly, Rav Avraham Pam explains that the entire purpose of a Jewish wedding, the bonding of two people who come together to build their home as one, is to produce a union that will revolve around and perpetuate Torah and chessed. That is the goal of a Jewish marriage. And so, if you bring joy to the bride and groom, you are helping them come together; the closer they are, the greater success they will have in brining out Torah and mitzvos and ruchniyus into the world. Thus, as a direct reward, you get the same thing, success in Torah, for you and your family!
When the Avos and Imaos got married, they had one goal and that was to bring out Klal Yisrael, a nation dedicated to service and commitment to Hashem and one that would learn, breathe and live the Torah. That is why the union of Yitzchak and Rivkah is compared to the teaching of the Torah by Moshe to the Jewish nation. It is the same objective.
The Mishna (Avos 5:21) says, “at age 40 one achieves binah, understanding.” Chachma, wisdom, is the raw facts, this is the written Torah. This is the trait of Avraham, who recognized his Creator at age 3. He got the facts. Binah, understanding, is the extrapolation and application of the raw facts. It comes from within but directly ties back to the information. Thus, it represents Torah shel Baal Peh, the oral Torah. This was Yitzchak and his exact age. The last level is that of daas, which is action and implementation. It is the synthesis of both the wisdom and extrapolation and the practical action to bring it out. This is the trait of Yaakov, who synthesized the traits of Avraham and Yitzchak.
It was the evil Samech Mem (the angel Samael who is often referred to as Samech Mem in order not to mention his full name) that caused Adam and Chava to sin. The seforim teach us that Samael is the Malach Hamaves, the Yetzer Hara and the Angel of Eisav, they are all the same creature. Samech Mem caused Adam to sin and Adam thereby lost his beautiful continence. Thus, years later, Yaakov stole the bechorah and berachos back from Eisav to get back that which was stolen from him (Zohar).
The Gemara Bava Basra (58a) hints to this passage when it says, “the beautiful countenance of Yaakov was a reelection of the beautiful continence of Adam.” The countenance referred to is obviously of a spiritual nature. What is interesting to note here is that Adam lost that countenance when he sinned. The Gemara (Nedarim) tells us that the wisdom of a man lights up his face. That means that Yaakov took back his spiritual heritage and thereby restored his countenance to be reflective of one who is happy due to his wisdom and his feelings of satisfaction for living his life according to Hashem’s will.