“Altogether
the total number of connections in the human
brain approaches 1015 or a thousand million million.
Numbers in the order of 1015 are of course
completely beyond comprehension. Imagine an area about
half the size of the USA (one million square
miles) covered in a forest of trees
containing ten thousand trees per square mile. If
each tree contained one hundred thousand
leaves the total number of leaves in the
forest would be 1015, equivalent to the
number of connections in the human brain!”