Book 3 continues with some more chapters about galaxies. In chapter 3 we are considering active galaxies. This looks at all sorts of the more weird end of the galactic spectrum. It considers galaxies that have active cores - these include Seyfert galaxies, quasars and blazars - and whether they are the same thing viewed from different angles. Active galaxies appear to be associated with early galactic structure, at least in some cases. I found it all a bit dull to be honest after the first few pages. Maybe galaxies aren't my thing - or I'm missing the point!
Then chapter 4 looks at the distribution of galaxies. The fact that the milky way is just one of a local group of galaxies that includes a number of others. Then our local group is part of a supergroup of groups grouped together. Beyond that there doesn't seem to be any further discernible structure to the universe.