Hebrew University Professor Emeritus and Israel Prize recipient Eliezer Schweid (1929-2022) is widely regarded as one of the greatest historians of Jewish thought of our era. In Siddur Hatefillah, he probes the Jewish prayer book as a reflection of Judaism's unity and continuity as a unique spiritual entity; and as the most popular, most uttered, and internalized text of the Jewish people. Schweid explores texts which process religious philosophical teaching into the language of prayer, and/or express philosophical ideas in prayer's special language - which the worshipper reflects upon in order to direct prayer, and through which flows hoped-for feedback. With the addition of historical, philological, and literary contexts, the study provides the reader with first-time access to the comprehensive meaning of Jewish prayer-filling a vacuum in both the experience and scholarship of Jewish worship.