I briefly mentioned this scene in my post just below about Margaret, but I've been thinking of the scene where Marianne and Margaret are walking on the hill, and Marianne asks her sister "Is there a felicity in the world superior to this?"
I wanted to touch on something else about that scene in particular.
I don't generally think of Jane Austen as writing in a paricularly metaphoric way, but I think there is a lot going on in this scene. First of all, the two of them are out there because they are "unable longer to bear the confinement" of two days of rain that kept them in the cottage. Elinor and Mrs. D. have stayed in the cottage to read and draw, and it's still cold and damp outside. Marianne is the instigator of this, and doesn't want to listen to any warnings.
And "In spite of Marianne's declaration that the day would be lastingly fair, and that every threatening cloud would be drawn off from their hills;"--Elinor and Mrs. D. won't come. But Marianne refuses to see the signs, in other words. She sees what she wants to see. (Interesting how Willoughby kind of echoes these words later, talking about Colonel Brandon "...he has threatened me with rain when I wanted it to be fine...")
Outside, Marianne and Margaret are behaving in a charmingly childlike way: they climb to the highest point, they laugh as they let the wind push at them while they try to resist it. The narrator calls them 'the two girls'.
And then Marianne asks "Is there a felicity in the world superior to this?" It is part of sensibility to really enjoy nature, but it's also such an innocent, childlike thing to say. Is there anything that could make them happier than climbing a hill and feeling the wind on their faces?
And yet, were Marianne to ask herself the same question only a day or a week later, she would have to say that yes, there IS a felicity in the world superior to running around on a hill with your kid sister.
But, they are caught unawares. They run 'with all possible speed' down the hill and Marianne falls--literally and figuratively too, I guess. Falls in love, falls into a whole new phase of her life, falls because she takes a "false step"...