Why is the 9 square grid ordered bottom to top? I find it strange that 'A' should be in the bottom left corner of the grid and not the top left (with 'B' and 'C' ordered either to the right or below it). 

Since the writing its self has a baseline sequence of left to right, then top to bottom; wouldn't it have made sense for the grid order to reflect this? I'm interested to know if there is a reason this isn't the case.