The Book of Vayikra is called “Toras Kohanim” – the Law of the Kohanim, because it deals in great detail with the sacrifices and the service in the Tabernacle. The Ramban – Nachmanidies – explains that Vayikra follows the Book of Shemos because Shemos was dedicated to the Egyptian exile, redemption and the building of the Mishkan – which completed the redemption. So now, G-d commanded Moshe about the sacrifices and taking care of the Mishkan. If the Jewish people would properly care for the Mishkan, they would gain and not cause its removal because of their sins.
There is a dispute between the Ramban and the Rambam – Maimonidies regarding the reason for the sacrifices. The Rambam says that the Jewish people had lived among the Egyptians and others who worshipped herd, sheep and goats. Therefore, G-d commanded us to slaughter these animals as sacrifices. This shows that the action which nations considered to be the greatest sin should be done as an offering to G-d and bring atonement for the people. This would be a medicine to cure the illness of false belief brought about by living as strangers in foreign lands.
The Ramban disagrees with the Rambam. The Ramban explains that we don’t know everything that G-d has in mind. The concept of sacrifices falls into this category. Sacrifices accomplish matters that are beyond human comprehension.
The approaches of the Rambam and the Ramban both teach us a fundamental lesson. There are commandments in the Torah for which we can understand the rationale involved in the Mitzva – honesty in business, don’t steal, don’t murder, relating the story of the Exodus from Egypt, Shabbos, wearing tefillin and tzitzis – to name a few. There are other commandments whose reasons are totally beyond our comprehension – not wearing Shaatnez (clothing that contains both wool & linen), why certain animals, birds and fish are kosher and others are not, why milk and meat are kosher when prepared separately but not when prepared together, the particular guidelines for tefillin – just to name a few.
As Jews, we have to act in the way that G-d demands of us in the Torah. We must do the mitzvos that are incumbent upon each and every one of us, whether or not we understand what is behind each Mitzva. People might think that certain commandments make no sense. They do make sense. However, they are not understood – to that individual or to people in general. But, that should not affect our service and dedication to G-d. The actions and thinking of the world, which can be very influential, should not influence us into acting in ways contrary to the will of G-d.
One of the ways to test a bird to see if it is kosher and fit for eating or diseased and not fit for consumption is to put it into a river and see if it can swim. If it swims with the stream, it is not a sign of kashrus. It might not have the strength to swim on its own. However, if it swims against the stream, then you know that the bird is healthy. It is a sign of life.
As Jews, we must show that we are alive. That often requires us to swim against the tide of the world. The world doesn’t like the fact that we are different. We have a Torah. We eat differently, we talk differently, we act differently and have different interests. We have to do what’s best for us. That means following G-d’s law, whether or not we understand it.