Comprises the following four parts. Part 1: An extended introduction to Jewish prayer in the Middle Ages; to the unique status of Pentecost in Jewish liturgy as the holiday commemorating the receiving of the Torah; and the multitude of messages conveyed by this holiday in connection with the polemic against Christianity with regard to the concept of 'the chosen people'. The introduction will also explain the structure of piyyutim in general, and 'Adun Imnani' in particular. The role of the illustrations placed alongside the piyyut in the holiday prayer books (mahsorim), will be considered too. Part 2: The piyyut in Hebrew and in English translation; an analysis of the liturgical and midrashic layers; and an analysis of its main ideas. Part 3: The commentary on the piyyut (about 25 manuscripts, from different locations) and its sources; annotation and translation into English of these commentaries; and an analysis of the conceptual world in which they were written and the messages they sought to impart. Part 4: A presentation and analysis illustrations of the piyyut; historical discussion of the piyyut within the manuscript context and the contexts of its usage.