Summaries are very useful things.
The Bible, along with most other ancient literature, uses summaries quite often. Even if we have very good memories, it's hard to carry an entire book around in our heads, or an entire library of coordinated books, as in the case of the Bible. Even quite literate people could not depend on being able to run to their bookshelf to look something up. As late as the Middle Ages, fifty or sixty books were considered a gigantic library, suitable for a major university. Now, in fact, we may have too much information available to us.