Hoyle uses the characters (specifically Sinclair) as mouthpieces to discuss the idea that time does not "flow" but exists as a four-dimensional spiral where all points are equally real.
Reverted to 1917, where World War I is actively raging. October The First Is Too Late
: Used copies with classic Paul Lehr cover art are available for about $8.00 at Postmarked from the Stars . October The First Is Too Late
: Collectors can find original hardbacks for approximately $9.99 $8.49 at eBay - retrogiant . October The First Is Too Late
If you are looking for a physical copy, several editions are available from various merchants: