The commandments of the Torah are divided into three general categories: eidos, testimonies; chukim, decrees; and mishpatim, laws.1

Eidos are those commandments that recall and/or testify to past significant events. Examples are Shabbos, Pesach, Shavuos and Sukkos.

Mishpatim are those commands — both positive as well as negative — that are also dictated by mortal understanding. Examples are the obligation to honor one’s parents or give charity, and the prohibition against stealing.

Chukim are commands that have no rational explanation. In commenting on the verse, “This [law of the Red Heifer] is the chukah of the Torah...,”2 Rashi3 notes the following: “Satan and the nations challenge the Jews, ‘What kind of mitzvah is the Red Heifer, and what rationale is there for it?’ The Torah therefore prefaces this mitzvah with a declaration that uses the term chukah: this is a decree ordained by G‑d....”

Indeed, among chukim themselves, the most puzzling of all is the command of the Red Heifer. Even King Solomon, the wisest of men, who could understand the Divine rationale underlying other chukim, could not fathom the reasoning behind the command of the Red Heifer, which brought purity to the impure and rendered the pure impure.4 Concerning this decree, he admitted: “I said, ‘I will gain wisdom,’ but it is far from me”5 — the command of the Red Heifer transcended even the extraordinaryintellect of King Solomon.

The terminology, “This is the chukah of the Torah,”rather than “This is the chukah of the Red Heifer,” indicates that the inexplicable decree of the Red Heifer is the Torah: it is a foundation for the entire Torah6 including its commandments. Even the commandments of eidos and mishpatim, the rational commands, are essentially expressions of the Divine Will,7 and as such they transcend logic — they, too, are chukim, just like the law of the Red Heifer. However, G‑d desired that the Divine Will underlying eidos and mishpatim descend and become clothed within rationality.

The same is true with regard to Torah.8 Even those matters in Torah that are comprehended by human intellect are, in fact, suprarational. After all, Torah is G‑d’s wisdom;just9 as no created being can comprehend his Creator,10 likewise it is impossible for any created being to comprehend His wisdom.

Knowledge of this matter is basic to one’s spiritual service of Torah and mitzvos. The performance of all mitzvos, the rational as well as the suprarational, ought to be motivated by kabbalas ol,accepting the heavenly yoke upon oneself and performing the commandments because G‑d has so decreed. This is mirrored in the text of the blessing made for all mitzvos: “... and He has commanded us.” The same is true with regard to Torah study.

This is why the rationale for the commandment of the Red Heifer remained concealed even from King Solomon; it was necessary that at least one command of the Torah remain in a state of chukah, thus indicating that the rest of the Torah and mitzvos are essentially similar — they, too, are chukim.11

Furthermore, if all Torah matters were to have descended to a rational level, it would be impossible for us to perform mitzvos with the feeling that we were doing so solely because they voice G‑d’s Will. Additionally, inasmuch as the performance of mitzvos would then be limited to rational understanding, it would be impossible for a Jew to reach the level of mesirus nefesh, total self-sacrifice for G‑d, a level that defies and transcends the limitations of intellect.

Based on Likkutei Sichos, Vol. XVIII, pp. 229-237.