“Va’yiChaD Yitro (And Yitro exulted) over all the good….” (Exodus 18:9)

And our Sages, of blessed memory, taught: [Yitro’s] flesh became covered in ChiDudin (goose bumps) . (Sanhedrin 94a)

All rejoicing is transient. For example, the joy of a wedding or a brit is only at the moment. If one considers the end, there is nothing in the world to rejoice over, for “Man’s end is…” (Berakhot 17a). Yet, if one considers the end of the end, he should be extremely joyous. This is because the final end—i.e., the ultimate goal—is very good.

Now see, this is only from the soul’s perspective, since from its perspective death is very good. As our Sages, of blessed memory, taught: “now see, it was very good” (Genesis 1:31)—this refers to… (Bereishit Rabbah 9:10). It is very good, because through it one comes to the ultimate good.

Nevertheless, when someone is a tzaddik, such that his body is clean and very holy, he can rejoice also with his body, even if he considers the end, since his body too is pure and holy. This is as it is written (Psalms 56:5), “In the Lord I trust… what can mortal flesh do to me?”—“mortal flesh,” i.e., the body, cannot cause him any harm. And as it is written (ibid. 16.9), “even my flesh rests securely.” The tzaddik is certain that it will be very good also for the body. Therefore, even when he considers the end, he can rejoice also with his body.

But [this cannot be said of] someone whose body is not all that holy, particularly a convert, for although his soul is extremely lofty, his body was formed from impure seed—and how is it possible to change this? It follows, that it is impossible for this person whose body is not all that holy, particularly a convert, to rejoice with his body when he considers the ultimate goal.

Thus, this is “Va’yichad Yitro over all the good.” Yitro rejoiced over all the good—meaning: even when he considered beyond the good. And this is “over all the good”—above and beyond the good. Although he considered this—i.e., beyond the good, namely, to the end—he was nevertheless extremely joyous. This is because from the soul’s perspective, even when one considers the end, it is very good, as mentioned above.

But “his flesh became covered in goose bumps”—specifically, “his flesh,” i.e., the body. On account of his being a convert, when he considered the end, his joy was not with his body. And this is: “his flesh became covered in chidudin”—specifically, “his flesh.”