Reggio's most important works are "Ha-Torah weha-Pilusufiah," "Mafteaḥ el Megillat Ester," and "Beḥinat ha-Ḳabbalah". The first, a religious-philosophical essay in four sections ("ma'amarim"), was written as an answer to the rabbis of the old school who protested against the establishment of the rabbinical college at Padua. It should be explained that Reggio applies the term "philosophy" to all studies outside the Talmud and rabbinics. Reggio not only endeavors to reconcile the Jewish religion with modern science, but attempts to prove that they are indispensable to each other. One chapter, entitled "Ha-'Olam weha-Adam," was republished by Martinet in his "Tif'eret Yisrael" (Bamberg, 1837). Another chapter, in which was discussed whether the Torah is in opposition to the Kabala, was stricken out by the censor. Later this chapter was plagiarized by S. M. Rosenthal, who published it in Fürst's edition of Leon of Modena's "Ari Nohem" (pp. 92–97, Leipzig, 1840).