ויט משה את ידו על השמים ויהי חשך אפלה בכל ארץ מצרים
Chazal (Midrash Rabbah/Shemos 14:2) ask from whence came this choshech, darkness. Rabbi Yehudah says it came from on High. It was a Heavenly/otherworldly darkness, as it says in Tehillim 18:12, “He made darkness His concealment, around Him His shelter.” (This means: even when Hashem intervenes in a swift and stunning manner in human affairs, He remains concealed [Ibn Ezra], or alternatively, man quickly forgets Hashem’s role in all that happens to him [Horav S.R. Hirsch]. The question is obvious: If the darkness that plagued Egypt was from Heaven – where in Heaven was it to be found? Is there darkness…
