Reb Yaakov Kamanetzky zt'l explained the mitzvah of pidyon haben. The Sforno (Shemos 13:2) states that before the pidyon, the child isn’t permitted to work. Throughout his life, he wouldn't be able to work if he didn't have a pidyon haben. Just as there is a halachah that one may not do work with an animal that is kodesh for the Beis HaMikdash, a firstborn is also holy, and he may not work. The pidyon enables him to be involved in the work of this world.
Reb Yaakov Kamanetzky asks that if so, what is the joy of a pidyon haben? Isn’t it better for the child before the pidyon haben, when he was holy for Hashem?
Reb Yaakov replies that before the pidyon, the child was living a spiritual existence, like when his soul was in heaven, but this isn't the purpose. We are meant to be in this world, struggle with the yetzer hara, and nevertheless, sanctify Hashem's name. Pidyon haben is a great simchah because it enables the child to interact with this world, and that is the entire purpose of creation.
Chazal (Pesachim 109a) say, בבשר אלא שמחה אין, "There is no joy without meat". It is repeated in the name of the Baal Shem Tov HaKadosh (see Baal Shem Tov al HaTorah, Bereishis, note 75) that Hashem's joy is from בשר, from people, בשר ודם. Hashem desires the service of human beings, who have challenges and tests over the service of the malachim. Hashem's pleasure and joy are specifically from them.
A hint to this concept is the pasuk (Shemos 10:9) נֵלֵ ךְ וּבִזְק ֵנֵינוּ בִּנְעָר ֵינוּ ֶׁהמֹש וַיֹּאמֶר, "Moshe said, 'With our youngsters and with our elders shall we go." Why did Moshe mention the "youngsters" before the "elders"? Generally, we give honor to the elders, and he should have mentioned them first!
Shevet HaLevi zt'l answers that even when Bnei Yisrael lived in the very impure land of Mitzrayim, they were cautious with their kedushah (see Shemos Rabba 1:28). As is known, when one is young, he has much greater and bitter tests to maintain the kedushah than those who are old. One grows from tests, so the younger generation was on a higher level than the older generation. This is the reason Moshe mentioned the youths first.
Chazal (Pesachim 8a) say, מן מצוה להבדלה אבוקה המובחר. Literally, this means that when we say the brachah האש מאורי בורא it is better to use a havdalah candle that has at least two wicks, so it will appear like a torch. Yalkut Garshuny ('ו אות) explains this Gemara b'derech remez. אבוקה can be translated as a battle or a wrestle. (See for example Bereishis 32:25, עִמּוֹ אִישׁ וַיֵּאָבֵק, "a man wrestled with him...") הבדלה can mean when one separates himself from bad deeds. Chazal say, אבוקה להבדלה, when one battles and wrestles with the yetzer hara to free himself from the bad, it is a המובחר מן מצוה, the most ideal accomplishment.
The holy sefer Avodas Yisrael (Haftarah Vayigash) writes, "There are many ways to serve Hashem. Firstly, the straight way, to learn Torah and to be involved in avodah and mitzvos all day long, and to afflict oneself by being parush, separated from the taavos and pleasures of this world. There is another path for those who want to be holy. This derech is to eat and drink and partake in these activities in a holy manner (see Shulchan Aruch, Orach Chaim 231, and the kavanos of the Arizal, and other holy sefarim). Certainly, those who can sanctify even the physical deeds they do and their taavos, their table is like a mizbeiach. This is an even greater form of kedushah. When one is occupied with Torah and tefillah, the yetzer hara isn't so strong to entice him that he should go off this good path and go on a bad path. This is because (Koheles 8:5) רָע דָּבָר יֵדַע לֹא מ ִצְוָה שׁוֹמֵר, "He who performs the mitzvos will know no bad.' But when one falls from his madreigah, and he desires to eat (or other taavos), but he breaks his temptation, and he doesn't eat and drink like an animal. Rather, he eats to satisfy his soul so he can serve Hashem, and have a heart that is open and wise in Torah, and other high intentions, then his avodah is even greater, and it creates a nachas ruach for Hashem yisbarach, a thousand times more."
Chazal (Bava Basra 7b) teach that tzaddikim don't have to pay the tax to pay for the construction of a wall to guard the city. The Gemara explains that they are protected without weapons, and without the wall, etc., because their good deeds protect them. Chazal learn this from the pasuk (Tehillim 139:18) יִרְבּוּן מֵחוֹל אֶסְפְּרֵם, "Were I to count them, they would outnumber the grains of sand." Rashi writes, "Just as the sand protects the world from the waves of the sea, so that the waves shouldn't flood the entire world, so do the deeds of tzaddikim protect them.
Reb Boruch Shimon Shneerson zt'l asked that there are many shields and protections in the world. Why do the pasuk and Chazal specifically use the mashal of the sand at the seashore, which protects the world from the sea? Why wasn't any other example used? He explains that each grain of sand on its own is nothing at all. It can't create any protection. But many grains of sand act as the greatest protection. Similarly, the good deeds of tzaddikim might appear small and insignificant when you look at each one individually. But tzaddikim have many good deeds, and this protects them.
Sometimes, our good deeds seem small and insignificant. But when you put them all together, they possess strength that can't be stopped. Each good deed and every time a person holds back from performing an aveirah, another grain of sand is created, and they unite and turn into a great force that can protect the entire world.
Or Zarua (siman 422) writes, "My heart tells me, I, Yitzchak the author, that just as a small rasha is not buried next to a big rasha, so, too, one shouldn't bury a tzaddik next to a chasid." A chasid is on a higher level than a tzaddik. A tzaddik keeps the Torah, but the chasid is on a higher level, because he also sanctifies himself with the permitted, and he makes gedarim, boundaries, לפנים הדין משורת. Therefore, they shouldn't be buried next to each other. This is written in Shulchan Aruch (Yorah Deiah 362:5), as well. They aren't buried together because they aren't on the same level.
We add that also when they are alive, one who sanctifies himself with boundaries to distance himself from aveiros, is on a much higher level than those who keep the Torah without this caution. An example of this is someone who guards his eyes before he is confronted with a test, so he won't come to be tested. There are many other examples. He is on a far higher level than even the good Yidden who keep the Torah, but without making these boundaries.
