I really love this because I think the person who wrote this was happy when they wrote it but something happened that caused them to add the ‘not’.
Just before nightfall I decided to take a walk outside. The sky was low, enveloping any object in its reach. It formed a dull, purplish haze - like nothing I’d seen before. The streets were empty. Not a single soul was out. It was oddly peaceful - imagining I was the only one left.