Based on a Naaleh.com shiur by Rabbi Beinush Ginsburg
The seven weeks of sefira connect Pesach to Shavuot. The central goal of Yetziat Mitzrayim was to receive the Torah. We were taken out of Egypt so we would be free to serve Hashem. This is expressed with the mitzva of sefira.
Rav Hirsch explains that on Pesach the Jews primarily experienced physical freedom, which is symbolized by the korban omer. Barley, commonly used as animal fodder, signifies physicality. The shtei halechem, the wheat bread sacrifice offered on Shavuot, symbolizes spiritual freedom. The Jews did not achieve complete freedom until they received the Torah. On the fiftieth day, when they finally attained the pinnacle of spiritual purity, they approach Hashem with human food. Rav Hirsch writes that the day after the Jews left Egypt they began to count sefira. This further demonstrates that the Exodus was only the beginning. It was not the goal.
The Orchot Chaim explains that we do not recite shehechiyanu on the mitzva of sefira because the shechiyanu on Shavuot covers it. The whole purpose of sefira is to count towards Shavuot. Therefore, no separate bracha is required.
Additionally, although there is a special mitzva to rejoice on the shalosh regalim, the Torah does not mention it in relation to Pesach. This is because the simcha of Pesach isn’t complete until Shavuot. The entire goal of Pesach is Matan Torah. The Ramban in Vayikra refers to sefira as chol hamoed. These seven weeks between Pesach and Shavuot link the two holidays together. Chazal refer to Shavuot as “atzeret.” Atzeret means to stop and hold on. It is usually used in connection to the closure of Yom Tov where we are exhorted to hold on to the holiness that was gained during the holiday. Shavuot is atzeret because it is the end of the period of Pesach and sefira.
Sefira is both a joyous and mournful time. As we happily anticipate Matan Torah, we mourn the passing of the students of Rabbi Akiva. Why did they die specifically during this time period? The Hegyonei Halacha explains that to properly prepare for receiving the Torah, a person must work on his middot. Indeed there is a custom to study Pirkei Avot during sefira. We need to think about why we are in aveilut, internalize the reason, and work to rectify our failings. The Gemara writes that the students died because they did not properly respect each other. These seven weeks are an opportune time to work on our relationships bein adam l’chavero.
We can learn from the death of the students of Rabbi Akiva the importance of mesora and how we have to be careful to keep it perfectly intact. Rav Aharon explains that if these students would have lived they would have been the future Tannaim and the baalei mesora. Respecting our friends means having objectivity to accept the truth of another opinion even if you did not think of that idea first. Rav Aharon explains that the students had a problem with their learning. They could not put aside their personal ego to concede their friend’s position even if it was true. If they would have lived, their mesora would have been corrupted because they were lacking in middot. Instead of passing on a corrupted tradition, they died.
The lofty weeks of sefira are meant to help us gradually ascend the ladder of self development so that ultimately we can reach the holy day of Shavuot with pure hearts ready to receive the Torah anew.