The book of nature is usefulness. The book of Life is Net Future Usefulness. The book of humanity is "usefulness to humans". Mathematics is useful to humans, and is a self-justified tome in the books of humanity. It is merely a primer in the book of Nature; useful for some species of moving, competitively evolving matter (counting offspring, seasons, etc), but generally only an emergent phenomenon of causal physics which we rarely and reluctantly separate from our filtering book of mathematics.