Kedushat Levi, Leviticus, Tzav

ענין חטאת ועולה חטאת קודמת לעולה, כי חטאת הוא אור ישר מעולם העליון לעולם התחתון. ועולה, הוא חוזר מעולם התחתון לעולם העליון ולכך עולה כולה כליל. וזו ויקרב את העולה ויעשה כמשפט, היינו כמו ר"ח תשרי האותיות הם למפרע בסוד אור חוזר ודו"ק (חסר): In Parshat Tzav, when the respective sacrifices known as ‎עולה‎, burnt offering, where the entire animal is burned up on the ‎altar, and ‎חטאת‎, sin offering for inadvertent violation of many ‎otherwise severely punishable sins are discussed, the Torah first ‎legislates details of the sin offering. The reason for this apparently ‎inverted order, is that although the ‎עולה‎ offering is considered as ‎of a higher order, the sin offering symbolizes what we have ‎elsewhere already described as the ‎אור ישר‎ direct light, original ‎illumination stemming from the highest celestial regions, whereas ‎the ‎עולה‎ symbolizesאור חוזר ‏‎, reflected light, light containing a ‎human response to the original light. The reason that the entire ‎body of the animal used in the ‎עולה‎ offering is burned up, so that ‎the ‎ריח ניחוח‎, pleasant fragrance rises heavenwards, is because it ‎proves that man has responded positively to the gift of the ‎‎“original light.”‎
This is also the meaning of the line in Leviticus 9,17: ‎ויקרב את ‏העולה ויעשה כמשפט‎, “He presented the total offering and ‎performed its ritual in accordance with the rules pertaining to it;” ‎The author hints at a parallelism with the letters in the word ‎תשרי‎ ‎in which the letters (excluding the last which symbolizes the ‎name of G’d) appear in the reverse order of the alphabet. The first ‎day of ‎תשרי‎, New Year’s Day, is the day on which we creatures ‎return to G’d in repentance, i.e. we send out ‎אור חוזר ‏‎,“reflected ‎light,” proof that we can respond to G’d’s great kindness in ‎having illuminated our universe with direct light from His ‎essence. ‎