Ancient Greek legend described by Plato, later hypothesized to be real, and depicted on a 1664 map by Athanasius Kircher.
To your top left the black & white chessball helps you to navigate home, find hints and other links. Hover in and out to show the navigation items!
Top Right and Bottom Right you either find + and – icons to navigate pages (top) and chapters (bottom), or other (self-explaining) Navigation Items. Hoevering the icons tells you also what they do. If no navigation at all appears, use scrolling!