Many commentators are troubled as to why the Torah chose to explain in great detail the laws of the sacrifices here in our Parsha rather than in last week's Parsha, Parshas VaYikra, where the Korbanos are originally introduced. If some of the details are presented, as they are, in Parshas VaYikra, why aren't all of them presented there? Rav Moshe Feinstein once explained that there is a principle in Halacha, presented by the Gemara in Chulin (דף ג:) and codified in the Shulchan Aruch (יורה דעה סימן א' סעיף א'), that even if we don't know that a particular Shochet, who slaughters meat, is an expert in the laws concerning the ways to properly slaughter and process Kosher meat, we are nevertheless permitted to rely upon his slaughtering and eat his meat since we have a rule that "רוב מצויין אצל שחיטה מומחין הן," meaning that most people who slaughter are experts at doing so. The Pri Megadim (שפתי דעת שם ס"ק ד') writes that we do not even have to investigate the qualifications of the Shochet, because there really are two rules operating here, the first being that most cows are Kosher, and the second being that most people who slaughter are experts. The reason for this latter rule seems to be that all Jews are aware of the concept that animals require a proper Shechitah for the meat to be considered Kosher, but they don't know all the laws. If one has any questions, therefore, he will surely ask, and if one does not ask, we may assume that he knows what he is doing. However, were most people not aware of even the fundamental idea of slaughtering, then this rule wouldn't apply. In a similar manner, therefore, the Torah first wrote in Parshas VaYikra about the various Korbanos so that all the Jews will be aware of them in general, and then, in Parshas Tzav, the Torah elaborated in great detail upon all the intricacies of the sacrifices that can be known only by those who devote their major time to the study of Torah.
Rav Feinstein concluded by noting that years ago, most students knew all the fundamentals of the Mitzvos because of what they experienced at home, and many of the Yeshivos were thus the centers primarily for in-depth study and thereby served to produce Torah giants. Today, however, many of our Yeshivos must also serve to acquaint many students with even the fundamental concepts, to strengthen their faith and commitment, and even to serve to produce civilized people. It has now become the responsibility of our Yeshivos to teach the very basics of Jewish existence, including moral and ethical behavior, which all Jews must live by.
This idea of teaching our students to act civilly with proper morals and ethics brings to mind an important lesson taught by Chazal. The Midrash in Devarim Rabbah (פרשה ה' סימן ב') cites a Posuk in Mishlei (ו':ו') which says "לך אל נמלה...," "go to the ant" and learn from its ways. What did Shlomo HaMelech, the author of Sefer Mishlei, see to learn from an ant? The Rabbanan say that he saw proper behavior since the ant avoids stealing. Rabbi Shimon Ben Chalafta then supports this with a story about an ant that dropped a kernel of wheat and although all the other ants came to it and smelled it, none would eat the kernel until the original ant came back and took it. We see from this Midrash the importance of honesty and integrity, concepts that must be stressed today, and taught in all of our Yeshivos. The lessons suggested in Parshas Tzav, namely, the in-depth concepts, can be fully understood and valuable only after the basics are presented.