** spoiler alert ** If you knew there was a bomb in a building, would you feel obliged to yell as loudly as possible to warn other people? The bomb explodes and the injuries are high and the death toll unimaginable. But then you have an opportunity to go back in time and prevent the bomb from ever being planted in the first place. Take things one step further...let's say that you stop the bomber before he even places his bomb...what else might change? Now you're dealing with what's known as 'the butterfly effect' - if a butterfly flaps it's wings in China, can it change the weather on the other side of the world?

"Pastwatch" takes that concept one step further by asking if you can change the course of one man's life, can you change the course of the entire world? That one man happens to be Christopher Columbus.

"Pastwatch" is about discovery, exploration and redemption. Columbus is believably passionate as we gain glimpses of his upbringing in Genoa, his early years in Portugal, and his ultimate journey to Spain where, for years, he lobbied King Ferdinand and Queen Isabela to support his adventures westward.

Pastwatch is a fictional organization tasked with utilizing cutting edge technology that allows people to view events in the past. Card's Pastwatch technology evolved over time, initially only allowing viewers to see events at a very macro level (historical world weather patterns initially), but developed eventually to see into actual human interactions. The most modern versions of Pastwatch technology allow viewers to watch humans interacting in full 3D.

Card moves the story swiftly by jumping through 15th century Europe and the future. With each jump, Card effectively evokes emotion and understanding from each characterization. Columbus is but one axis upon which the story revolves. The other characters are instrumental in the analysis and discovery of the ability to change the past. Tagiri focuses her Pastwatch career around the study of slavery. Kemal made one of Pastwatch's early and most fundamental discoveries when he found an individual who very plausibly was the basis upon which Noah, Gilgamesh and other world flood myths stand. Diko and Hunahpu are at the center of a new generation of pastwatchers.

Card has an uncanny ability to explore deep and influential topics while unraveling his narrative in an interesting and attainable way. Once the idea of time travel emerges, the characters debate its risks and rewards, but not for a moment did it feel bogged down in pseudo scientific mumbo jumbo. Likewise, there's much debate over slavery, European-based religion, and new world religion, and the speculation of alternative futures for Earth, but they blend seamlessly with the plot and merge well with the jumps into Columbus' inevitable journey across the Atlantic.

Card approaches his plot-lines very intelligently, but I found a few gaps in the characters' rationale that ultimately leads to the time travel adventures into the 15th Century.

The saga of "Pastwatch" is a remarkable book. I'm such a fan of exploration-era historical novels AND science fiction, that I'm ashamed to have never come across it until recently. It's truly a terrific read and I highly recommend it.

One note: the pastwatch concept originates from Card's short story called "Atlantis" which delves deeply into Kemal's identification and discovery of the "original" Noah. It's a very good standalone and rewarding work, and while it's not a necessity to read before "Pastwatch", it adds to the aura and myth that surrounds Kemal.