Why is the whole of 'Dracula' written in journals and letters?

Right, I'm basically just going to copy out what I wrote down in class on Tuesday...

One of the reasons why the text is written in journals and leters is to try and put across the idea of versimilitude, that the text itself is real. We know that Bram Stoker wanted Dracula to seem like a true story as he writes a foreword saying, "All needless matters have been eliminated, so that a history almost at variance with the possibilities of latter-day belief may stand as simple fact." Making the story seem real, is key to the novel as the reader must be forced to suspend their disbelief, through an appearance of non-fiction, "12 May- Let mebegin with the fact", so as to enjoy the text and the supernatural content that it covers, "...thus using every projection and inequality move downwards with considerable speed". Dracula is a book about Vampires so Bram Stoker had to persuade his aidience to distrust their Victorian sensibilities in order for them to fully engage with the text. The letters and diary entries that Soker uses are the mechanisms that they could have related to and trusted.

I would write a little more about how the form of the text uses diary entries and letters to give a sense of privacy (and also invasion of privacy by the audience being party to these personal documents) HOWEVER Ronnie currently has my copy of Dracula. I leant it to her out of the kindness of my heart when she no-showed on Tuesday and it's yet to be returned. Disgraceful behaviour I know. But the sum of her actions basically are I can't reference the text as I haven't got a clue how to get the kindle version back to chapter 5 without losing my current place soo... that will have to wait for another time.
Toodles.