Just found out about your Shadal series here -- kol hakavod! With regard to the question you raised about the Yovel superseding the previously declared halakha as to the length of a slave's service, it seems to me that what Shadal meant is simply that some halakhot were transmitted to Moshe sooner and some later. Another good example may be the basic laws of inheritance that were subsequently modified in the wake of the complaint of the daughters of Tselofchad.

<p>Hi Dan!</p> <p>Good to hear from you. According to you, how would Shadal understand the point of a&nbsp;law written in the Torah and then modified soon after. He writes often of&nbsp;the Oral Torah doing so, but why would "two versions" be in the Written Torah?&nbsp;<br /><br />The difference between here and the Benot Tzelafchad is that here, there is an "uprooting" of the word "le'olam", while there, the new law could be said to have been "unstated", where a father only has daughters.</p>

Not sure how to answer you question. Shadal's comments in Lev. ch. 25 re Yovel and slaves do not address the issue of why these provisions were not announced together with the provisions in Mishpatim. We tend to view the Torah's provisions as a unified system and organic whole, not like a secular law code that is continuously added to and amended by a human legislature. But at least during the 40 years in the desert, can't we say that the written Torah provisions only gradually became one system, perhaps in keeping with the opinion in Gittin 60a that "Torah megillot megillot nitnah"?