Hundreds of years ago, Celestial Navigation was treated with secrecy, because a nation whose navy could navigate properly could find new routes to places where spices and other valuables could be obtained.
More importantly though, a navy that could navigate would be able to have its ships rendezvous, to form a powerful armada that enemy ships could not survive against.
Yachtsman/author Gene Grossman breaks through the mystery of Celestial Navigation, and gives a plain-English explanation of the subject, so that you can go ahead without trepidation and learn the subject more fully.
And towards that end, Gene Grossman's Magic Lamp Productions has made its several DVDs on Celestial Navigation viewable for download from your library, just like this eBook was. Check your library's listings for those titles.