Jonathan Henry Sacks, Baron Sacks, (Hebrew: Yaakov Zvi, יעקב צבי), Kt (born 8 March 1948) is a rabbi, philosopher and scholar of Judaism.He was the Chief Rabbi of the United Hebrew Congregations of the Commonwealth. As the spiritual head of the United Synagogue, the largest synagogue body in the UK, he was the Chief Rabbi of those Orthodox synagogues, but was not recognized as the religious authority for the haredi Union of Orthodox Hebrew Congregations or more secular movements such as Masorti, Reform and Liberal Judaism. As Chief Rabbi, Sacks formally carried the title of Av Beit Din (head) of the London Beth Din.Sacks was influenced by Rabbi Menachem M. Schneerson, who he called "one of the greatest Jewish leaders, not just of our time, but of all time."