Original sentence: is arguably Fort's most popular book, perhaps due to the fact that the book deals with an extremely wide and diverse range of phenomena (as can be seen below), and Fort by now has a clearly established (if still somewhat shaky) theorem to go on
Edited sentence: is arguably Fort's most popular book, and it's easy to see why: the book deals with an extremely wide and diverse range of phenomena (as can be seen below), and Fort by now has a clearly established (if still somewhat shaky) theorem to go on