Q. How can Eliyahu Hanavi be present at every bris, even a malach can’t be in two places at the same time?

A. Od Yosef Chai (Pinchas) quotes from the Idra Rabba (at the end) that Eliahi Hanavi apologized to Rabbi Shimon bar Yochai for being unable to attend the learning of the Idra. He explained that on that day, Hashem had send him to perform miracles on behalf of Rav Hamenuna Sabba. Upon what Maharitz wondered, does not Eliahu attend every bris mila, demonstrating so that he is able to be present in a number of different places at the same time? He explains, that at the bris ceremony there is only a “nitzotz” or spark of his presence, and that he is able to achieve for many. However, performing miracles for Rav Hamenuna or learning the Idra, requires his full attendance

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a