Interestingly, while Brackett's novel is all action, constant and non-stop, careening from one heart-racing set piece to another, Silverberg's book is pretty much no action at all, basically all talk.

Both books are tremendously exciting and suspenseful, though. While opposite in so many ways, they're both page-turners.

The The Nemesis from Terra is really a fantasy novel wearing a slight sci-fi disguise but Collision Course is true science fiction.

The basic story is that in 28th-century Earth a faster than light drive has completed its first successful run. The ship's crew has zipped over to another galaxy and back again.

This is big news because humans have already colonized all the nearby planets and are naturally planning to take the rest of the universe once that becomes practical.

But the first time out, they run into an alien species who are doing the exact same thing.

So a diplomatic mission is sent out to discuss the matter with them. Contact is made, the alien language is learned and a proposal to share the universe with this other culture is made.

And the aliens say nope. You keep what you've already conquered but everything else is ours. Or else.

That's the set up. The mechanics of both the journey through space and the journey through communication with previously unencountered life-forms, as well as the personalities of the characters, who are well drawn and also serve to make some observations about religion, science, psychology, etc. are the bulk of the book.

There is a significant bend in the plot that I won't reveal because it's a cool surprise. But the story is similar to Childhood's End, though I thought it was better than Childhood's End.

This future society is governed by officials called Archons and early in the book Silverberg rattles off the names of several of them. Archons of Education and Health and Agriculture and so on. It's almost certainly a reference to Sherlock Holmes that the Archon of Security is named Lestrade.

The first line is "Only a month before, the Technarch McKenzie had calmly sent five men to probable death in the name of Terran progress".