For Friedman, 'Bible' refers to the Hebrew Bible (Tanakh), which corresponds to what Christians call the Old Testament, although there are some differences. The question of who wrote the text is probably not one that has occurred to many secularists or Christians, and one might think it would be of interest only to biblical scholars. But knowing when a text was written and by whom may make a lot of difference to how we interpret what it says. Friedman has managed to produce a book that reads like a detective story and will hold the interest of anyone who recognises the central importance of this book in the history of Western culture.
Moses has traditionally been held to be the author of the first five books of the Bible (Genesis, Exodus, Leviticus, Numbers, and Deuteronomy). But difficulties with this ascription have been recognised for many centuries, and in the eighteenth century a consensus was reached that there were two separate sources for this material.
This is explained by historical events. After the death of King Solomon his successors were not able to hold the kingdom together and this resulted in the formation of two independent kingdoms, Judah in the south and Israel in the north. They had similar but not identical religious beliefs and traditions. In 722 BCE Israel was destroyed by the Assyrians. Many of its inhabitants were abducted or exiled (resulting in the idea of the ten lost tribes of Israel), while others escaped south to Judah, bringing their religious traditions and texts with them.
The two sets of texts were then combined into one, but they can be separated by careful analysis. In Judah God was known as Yahweh (Jehovah) while in Israel he was Elohim.The two sources have therefore been given the names J and E. But in the early nineteenth century it was realised that E is itself composed of two sources, one of which has priestly characteristics and is therefore labelled P. All three sources, J, E, and P, are found in the first four books of the Bible. The fifth book, Deuteronomy, has a different author, labelled D. He was a priest but from a different background from P, to whom he was hostile. Deuteronomy was said to have been found in the Temple by a priest, Hilkiah, in 622 BCE.
The story becomes more complicated at this point because of the defeat of Judah by the Babylonians in 587 BCE. The Temple was destroyed and most of the prominent Judeans, including the priests, were transported to Babylon, although some escaped to Egypt.
In 538 the Babylonians were defeated by the Persian king, Cyrus the Great, and Judah became part of the Persian empire. Cyrus allowed the Jews to return to Jerusalem and to rebuild the Temple. There seem to have been two D authors, one pre-exilic and one post-exilic; both were priests.
Friedman refers to the post-exilic period as an Age of Mysteries, since we know very little about what happened after the return from exile. One mystery concerns the Ark of the Covenant, which is supposed to have held the tablets on which the commandments were written. There is no information about what happened to it. The second mystery is the disappearance of the Davidic dynasty, which was promised to last for ever. Another post-exilic difference is that there were no more great prophets after this time.
There is also much that is mysterious about the construction and contents of the second Temple. Friedman has a theory about these things, based on what he thinks is a connection between the Temple and the Tabernacle—the sacred Tent that, according to Exodus, the Israelites carried with them during their forty years' wandering with Moses in the desert.
The final stage in the production of the Bible was the combination of all its elements to produce an artistic unity. This was done by someone whom Friedman describes as a redactor, who was also a priest.
Friedman has done an excellent job of making this complicated material both interesting and comprehensible. He is fairly confident that he has been able to identify several of the Biblical authors, but I won't spoil the suspense by listing his answers here. The book is certainly worth reading, whatever your religious beliefs or lack of them. It isn't essential to have a Bible at hand when reading, although if your memory of the basic structure of the Bible is hazy you may wish to refer to Wikipedia to remind you.