Wilhelm – addressee of all the letters
Many different aspects of human interaction with landscape: impulse to control the landscape through gardening, desire to reproduce nature in all its glory through painting or writing – compare to Wackenroder’s letter where he despairs of being able to describe the landscape – the insufficiency of human art to do justice to nature. Also, there is a major rift between “culture” and “nature”. This is especially evidenced in the ball scene when Werther and Lotte go onto the balcony to watch the storm. They leave “culture” behind them in the house and enter a kind of liminal space between “tamed” culture and “wild” nature, whose power is represented by the storm’s intensity. However, their understanding of the natural is mediated by their cultural associations. Klopstock is the (human) filter through which they observe and understand nature. Klopstock = Claude glass
Also, this "flight from society" is symptomatic of the larger context of the novel. Werther's entire experience in Wahlheim (hello, placelessness!) is the result of his inability to function in society. Much of his movement is outward - going out to Wahlheim, going out of the ballroom, going out into the woods - and away from civilization. The problem with his experiences in nature, though, is that his experiences are always mediated through someone else's experiences and ideas - first Plato, then Klopstock, then Ossian (whose own writings were fictional, it turned out). There are layers of artificiality in Werther's behavior that make any kind of authentic experience impossible.
Also, Werther’s experience of landscape is marked by his own moods – or his moods are marked by what nature is doing around him. In the letter of 10. Mai, he feels at peace with nature – its peacefulness and happiness mirrors his own. At other points in the novel, though, nature takes on a dangerous, violent force that mirrors changes in his own attitude/experience. Landscapes are specifically created in Werther to mirror and echo his attitudes. Floods –Abgründe, etc.
Epistolary Novel – however, also framed by the fictional editor. The reader almost takes the place of Wilhelm, the friend to whom Werther addresses his letters. We only get half of the correspondence which also reflects the entirely self-absorbed nature of the protagonist.
Frequent allusions to other writers assume a reader that is educated and informed in a similar way as Werther and Lotte are. The references don’t mean anything without their context intact in the reader.