"This is how you lose the time war". A science fiction short book where rival agents send each other letters and attempt to thwart each other. It is also has

"This is how you lose the time war". A science fiction short book where rival agents send each other letters and attempt to thwart each other. It is also has some of the most beautiful prose/poetry I've ever seen that made me re-read each section over and over. I've been an avid reader since childhood and this is the first book to have that impact on me. Not at all what I was expecting.