And that, perhaps, is the real infinity: not the equations, but the spaces between the page numbers.
But then look closer.
Every good index ends on a quiet note. The last entry in my edition is , referencing Hardy’s famous rating of mathematical talent on a scale from 0 to 100—where Hardy gave himself a 25, Littlewood a 30, and Ramanujan a 100. It is the perfect closing note: the void from which all numbers spring, and the man who filled it.