This is a list of mathematics books I find particularly accessible, interesting, or beautiful. Because I am not a mathematician, it is aimed at non-mathematicians. I don't pretend to understand any of them.
See also my (nascent) Physics for Liberal Arts Majors list.
Please suggest, if you know works that would fit here.

Have you ever looked at G. H. Hardy's *A Mathematician's Apology* (1940)? It's probably one of the most-read essays among mathematicians. It's written by a great mathematician as he truly realizes that his powers are fading. (Some mathematicians take this especially hard, Lang on your list is another famous example.) This colors its tone and it has some controversial statements (e.g. "mathematics is a young man's game") that have been endlessly debated in tea rooms and grad student offices, but it expresses the raw emotions and special motivations of a pure mathematics researcher better than anything else I'm aware of. I've always liked it, but long thought it to be a too niche for general consumption. However, a few years ago I was shocked to found that the poet/memoirist Mary Karr not only really loves this work, but even hands a copy to her students as they graduate, as a reminder that "we're all in the same arena" when it comes to the creative struggle. Since then I've been recommending it more freely.