This book is organized into three sections - Vision, Debate and Space. The Vision is Gerald O'Neill's domain - progressing from broad propagation to technical details to anecdotes, The Debate section is probably the most unique to this book since no one else has published the highly intelligent attacks that have been stung into life by the Space Colony Idea. And the third section - Space - is natural history, accounts from people such as astronaut Schweickart and space scientist Sagan and politician Brown. Finishing, if you please, on a note of reality.