Musar for Yoma 57:8

וישלחו מן המחנה . What is meant is that והיה מחניך קדוש, the impure, should be sent from all three camps, as the situation required, in order to comply with the Torah's instructions in Deut. 23,15, והיה מחניך קדוש, "your camp shall remain holy." The Zohar there explains that the reference is to the 248 limbs of a person which make up his skeleton and which must retain their sanctity. This is hinted at in our paragraph. There are three camps and they represent respectively the head, the heart, and the stomach. The head is the seat of the brain and of all thoughts, and this domain must not be polluted by even the most minor degree of impurity. Our sages have already taught us that the הרהורי עבירה, impure thoughts and intentions, are more dangerous morally than the actual impurity caused by committing the sin (Yuma 29a). There follows the camp of the Levites, which is comparable to the heart of man. Obviously a good and pure heart is to be maintained at all times. The third camp is comparable to man's stomach and intestines, an area vital for converting food into energy, and discharge of that which cannot be used constructively. This area is somewhat ugly; it reminds us constantly of the bodily aspects of man and our tragic inability to remain alive without the body. Nonetheless, anyone who suffers from severe types of impurity must leave even that part of the camp. The moral lesson of all this is to sanctify oneself by means of one's food intake or abstention from it. The Jew is commanded to observe modesty even when he performs biological functions that are necessary, such as excretions of undigested food. All of these rules are designed to expel serious impurities.

Regarding "thought" our Sages already mentioned in the beginning of our Beraitha: "'you shall keep yourself from every evil thing' (Devarim 23:10) - From here R. Pinchas b. Yair said that a person should not have [impure] thoughts in his heart, and thus bring himself to have impurity at night" (Ketubot 46a). They further said: "thoughts of sin are worse than the sin itself" (Yoma 29a) and scripture says explicitly: "evil thoughts are an abomination to G-d" (Mishlei 15:26).

Remember that there are sacrifices parts of which may be consumed by the altar, the priest, and the owner. Examples of such sacrifices are the so-called peace offerings, שלמים. Other sacrifices may be eaten only by the priests in addition to the parts offered on the altar; examples of these offerings are different sin offerings called חטאות ואשמות. Their blood is sprinkled on the altar, and the אימורים are burned up to atone for the sin committed by their owners. The קרבן עולה, on the other hand is offered up whole on the altar, no part of it is eaten, even not by the priest. No one was allowed to derive bodily gratification from the עולה, because it atoned for sinful thoughts rather than for sinful actions. The sin had remained in the realm of the נפש, the intangible part of man. It had not touched his flesh. It is therefore appropriate that the entire animal which represents this sin should be converted to something intangible, i.e. רוח. When we keep this in mind we understand the statement of our sages (Yuma 29a) that הרהורי עבירה קשים מעבירה, "the contemplation of the sin is more serious than the actual execution of the sinful deed." Some sacrifices had to be brought from male animals only and others again from female only. The Zohar explains that the sacrifice of a male animal signifies an affinity between Heaven and earth which originated in the Celestial Regions, whereas the sacrifice of a female animal signifies an affinity between our region and the Celestial Regions which originated on earth.