Rabbi Yakov Haber
Midrash Tanchuma (1) introduces this week's parasha with the following teaching:
This Midrash teaches how the mishpatim, besides being important in and of themselves, can also lead to tzedaka, charity, and kindness as in the example where the simple act of fulfilling the mitzvos of p'rika (unloading) and te'ina (loading) can make sworn enemies into friends. On one level, this is an example of the famous dictum of Chazal in Pirkei Avos (4:2), "mitzvah goreres mitzvah - one mitzvah leads to another."
However, the logic of the helper donkey-driver seems difficult. If he is sensitive to the commandment of helping even his enemy load and unload, why is he not concerned about his initial violations of "Do not hate your brother in your heart" (Kedoshim 19:17) and "Do not bear a grudge [toward] members of your nation" (ibid. 18)? Ultimately, the verse itself, commanding the one who hates his fellow-Jew to help him, assumes exactly such a situation: that one is who is violating the prohibition of hatred is nonetheless charged to assist his enemy.
A possible approach to resolve this difficulty is that the Torah informs us not to fall into the trap of snowballing sin, that of "aveira goreres aveira" (Avos ibid.). A teaching from the Vilna Gaon informs us that a heretic not only gets punished for his heresy but also for his not making b'rachos on food! Just because one is sinning in one area cannot and should not permit him to sin more. "Shall one who ate foul-smelling food eat more of it?!" (Shabbos 31b). A curious halacha highlights this point. One who climbs a tree on Shabbos unaware of the Rabbinic decree forbidding this act may climb down. However, one who climbs up knowing it is forbidden (b'meizid) may not climb down (Shulchan Aruch Orach Chaim 336:1). The question is obvious: If he did not listen to the directives of halacha going up, he is not likely to listen going down either! But the halachic system assumes that sin is an aberration. Of course, any given sinner might not obey the Rabbinic directive to stay in the tree the whole Shabbos, but the halachic norm assumes that he will. Violating the halacha in one instance does not permit a subsequent violation. As such, the halacha deals with such situations as well, even if this ruling is not as practical as other halachos, at least to teach us this important lesson.
Another approach is that the assumption of the Midrash and ultimately the passuk is that it is more likely that a person would violate chovos hal'vavos (required emotions or thoughts) than chovos ha'eivarim (required actions). Prohibited thoughts and feelings are more difficult to refrain from than prohibited actions. Even the enemy who indeed is in violation of "lo tisna es achicha bilvav'cha", a sin of emotion, is reasonably expected to assist his enemy when he is in need, a mitzvah of action.
The Torah teaches us another message as well. How can the Torah prohibit thoughts and feelings? Aren't these automatic reactions that cannot be controlled? The Torah here provides for us one answer. Many sources point out that it is not the momentary feelings of hatred and distance that are naturally felt when one is harmed by another that the Torah prohibits; what is prohibited is to allow these feelings to settle in long term. But how does one prevent these longer term feelings from settling in? And if they did, how does he rid himself of these feelings? Here, the Torah provides an effective solution. Act kindly, then you will think kindly. If you want to reconnect to an enemy, act kindly to him, something that is much easier to accomplish than directly removing the bad feelings. Once you do that, it is likely that this will lead, if not immediately, then at least over time, to a removal of the ill-will harbored.
This idea seems to be highlighted by the Gemara (Bava Metsia 32b) which tells us "oheiv lifrok v'sonei lit'on, mitzvah b'sonei k'dei lachof es yitzro - if one is confronted with a conflict of helping a friend to unload his donkey or his enemy to load his donkey, the enemy takes precedence in order to subdue his evil inclination (meaning to help overcome his hatred)." This is true even though p'rika normally takes precedence over te'ina because of the tza'ar ba'alei chayim, alleviating the pain of the animal, involved.
This theme is also reminiscent of two central ideas presented by two Torah giants in different eras: Sefer HaChinuch and Rav Eliyahu Dessler. Seifer HaChinuch teaches countless times that "acharei hape'ulos nimshachim hal'vavos - after the actions follow the thoughts and feelings". Although the contexts in which he presents this idea generally relate to mitzvos bein 'adam laMakom the same principle can apply to mitzvos bein 'adam lachaveiro. Rav Dessler (Michtav Me'Eliyahu vol. 1) in his famous Kuntres HaChessed presents the approach that love is generated by acts of giving and is not necessarily caused by being a recipient of kindness. The very word ahava is related to the word hav which is Aramaic for "give". When one feels disconnected from someone, he should not wait for that person to approach him or to be kind to him. He should give to him first, and, over time, he will feel love toward him. Ultimately, that will solidify the relationship in both directions.
Through the Torah's emphasis on mitzvos ma'asiyos, commandments of action, Hashem guides us toward the path of perfection in all aspects of the human personality: thought, feelings, speech and deed.
 I assume the d'rash is from the phrase "mishpat utzedaka". See Eitz Yosef for an alternate interpretation.
> Gemara P'sachim (113b) gives a different interpretation that the verse speaks of someone whom you are allowed to hate, but the above Midrash assumes that the verse speaks of a case of prohibited hatred since it advocates and lauds the removal of the hatred. Such also seems to be the assumption of R. Nosson in Mechilta (to 23:4) and the Sifrei (Ki Teitzei 225). See Malbim in both places.
 A similar point emerges from the halacha that one who violates Shabbos willfully may not benefit from the object of his violation ever or at least until after Shabbos (See Shulchan Aruch Orach Chaim 318:1 and Mishna Berura 7).
 His essay of course needs to be read in its entirely to be fully appreciated. Here, we just give a brief synopsis in the context of the above Midrashic teaching.