p style=text-align: justify;In an autobiographic note Charles Robert Darwin (February 12, 1809 #8211; 1882) remembered a childhood wish:/pp style=text-align: justify;#8220; It was soon after I began collecting stones, i.e., when 9 or 10, that I distinctly recollect the desire I had of being able to know something about every pebble in front of the hall door#8211;it was my earliest and only geological aspiration at that time. #8220;/p a href=http://www.scientificamerican.com/blog/post.cfm?id=darwin-the-geologist[More]/a