thinking about time

How can you show time? Is it linear or does it move both horizontally and vertically... Does time intersect, or loop, overlap? Did each event cause the next one? a reaction, an advancement? What are important dates/milestones? How do they look different than the other dates. How do you show time in using scale, color, foreground background shifts...

data flow 2 (check out the preview)
http://www.improving-visualisation.org/visuals

muriel cooper