Don’t Eat the Mincha!
One of the offerings in the Bais Hamikdash was called a Mincha. It mainly consisted of flour and oil. When a person brought this offering, a handful of it (“Kometz”) was burnt on the Altar and the remainder was consumed by a Kohain.
There is one notable exception to the requirement to eat the Mincha. When a Kohain brings his own  Mincha, he is not permitted to eat any of it, as the Torah states in this week’s parsha. The entire Mincha must be consigned to the flames of the Altar. This requirement to burn the entire offering when brought by a Kohain is restricted to the Mincha - a flour offering. It did not apply to a Kohain’s animal sacrifice. 
Why wasn’t the Kohain allowed to eat and derive benefit from his own offering? Why was he treated differently from any other Jew, a portion of whose Mincha was eaten?
Maimonides, in his Guide for the Perplexed, and the Tosphos commentary explain that if the Kohain partook of his own flour offering hardly anything would have been offered, for only a handful of flour is placed on the Altar. In the case of an animal sacrifice more significant portions of the animal were placed on the Altar.
It is, however, still difficult to comprehend why the difference between animal and flour offerings should yield such a disparate result:  the Kohain may eat of his own meat offering but not of his flour offering.
Furthermore, the Shaloh asks, if our fear is that people will think that his offering was self-serving, leaving virtually nothing for G‑d or other people, why couldn’t he just give the unburnt Mincha portion to another Kohain? Why did it have to be totally consumed by the fire of the Altar?
He Offers His Soul
The Rebbe provides another explanation for the requirement that the Kohain’s Mincha be burnt. The Kohain was expected to be on a more spiritual level, with a life devoted exclusively to spiritual matters. The Kohain demonstrated his detachment from the physical world when he did not consume his own offering. The Kohain had to demonstrate that his offering of the Mincha was not motivated by any ulterior motive. He could not personally benefit from it.
We still have to understand why this requirement did not extend to animal sacrifices and why  the Kohain couldn’t just give his Mincha to another Kohain?
To answer these questions, we must understand the significant spiritual difference between animal and meal sacrifices.
The meal sacrifice was called the offering of a poor person, one who could not afford to bring a more elaborate offering to the Temple. On the surface, it would seem that a poor person’s modest offering would be inferior to the more expensive and elaborate animal sacrifice.
The truth is otherwise. The Torah describes the Mincha offering with the preliminary words:  “When a nefesh person [literally: soul] offers a Mincha …” Rashi explains that this expression suggests that when a poor person, who could only afford a flour offering, brings his offering he is actually giving much more of himself than the rich person. When an affluent person brings an offering, he offers his possessions and resources to G‑d. When a poor person brings his humble Mincha he gives of his very soul.
Moshiach: The Poor Man?
This can help us understand why Moshiach is referred to as “a poor man riding on a donkey.” His poverty is usually understood to mean that he will come even if the Jewish people are in a spiritually impoverished state.
In addition, Moshiach’s poverty is understood as describing his profound humility.
In light of our discussion of the poor man’s Mincha offering one can suggest that there is a third way to explain the characterization of Moshiach as a poor man. While most good people, including our leaders, give of themselves for noble and holy causes, Moshiach is singled out because he brings his very soul. There is not a single atom of his body and soul that he does not dedicate towards the overarching goal of bringing an end to Galus/exile by ushering G‑d’s totally unobstructed presence into our world.  Moshiach does not rest a moment from this holy labor. As the Talmud (Sanhedrin) states, Moshiach cannot bear to wait even an extra second to bring on the Redemption once G‑d gives him the signal to do so.
The Mincha offering is the symbol of the spark of Moshiach we all possess. It is a reflection of the essence of every Jewish soul, which is prepared to give of itself totally to G‑d and in the service of his or her people. This includes doing everything in our souls’ power to hasten the Redemption.
The Mincha-Moshiach Prayer
The afternoon prayer is known as Mincha.  Itis the shortest of the three daily services and it is usually said during the work day; often, hastily.
Yet the Talmud states that it is the most significant of the three daily prayers.  G‑d responded to Elijah’s pleas only after he prayed the Mincha service. Why is the Mincha prayer so special and why is this afternoon prayer in particular named Mincha?
Our Sages teach us that the Patriarch Isaac instituted the Mincha prayer service. Isaac was himself a sacrifice, whose entire being was consumed by his devotion to G‑d. The Talmud (Zevachim 62a) states that when the people built the Second Temple they identified the place for the Altar by seeing the ashes of Isaac there. This is understood to mean the ashes of the ram that replaced Isaac as a sacrifice and was considered as if it were Isaac’s own ashes.
Isaac personified the Mincha of a Kohain that is totally consumed.
It is for this reason that the Talmud states that in the Messianic Age we will refer to Isaac, and only Isaac, as our father (see last week’s essay). Isaac singularly personified total and all-consuming devotion to G‑d. This is an identifying characteristic of Moshiach and it is at the root of the Kohain’s need to have his entire Mincha consumed by the fire of the Altar. The Kohain channeled the energy of Moshiach, “the poor man.”
This idea helps explain why the Kohain could not give the flour of his offering to another Kohain. If he did so, it would detract from the message that a Kohain must channel the Moshiach-aspect of his soul and consign his entire flour offering to the flames of the Altar.
While we wait for the construction of the third Bais Hamikdash we must strive to internalize the message of the “poor man,” by focusing all of our energy on bringing the Redemption. Translated into practical terms that does not mean we should cease engaging in mundane activities but rather we should seek to find the spark of Moshiach and Redemption in everything we do.