Originally published in JJSO 29:1 (1987), pp. 68-9. Nahum M. Sarna, Exploring Exodus, xii +277 pp., Schocken, New York, 1986, $17.95. Following the very helpful and hugely successful guide to the first book of the Bible, Understanding Genesis, Dr Nahum Sarna now provides a guide, on the same lines, to the second book of the Bible. The…