American English, like many other languages from the European area, contains vowels and is
read from left to right.  Arabic and Hebrew, on the other hand, do not contain vowels and are
read from right to left.  There is apparently a connection between the presence of vowels and
the direction of reading.  The history of Greek points to this conclusion because at one point it
had no vowels and was read from right to left.  After vowels were added, the process of
evolution started to cause it to change to a left to right orientation.

Chinese is a pictorial written language and is read from bottom to top and from right to left.

Did you ever pick up a magazine just to browse through it and find yourself mainly looking at pictures?  
Did you catch yourself sometimes flipping pages from the back of the magazine towards the front?  You
were naturally going from right to left when seeing images.