H. Poincare. Value of science
F. Klein. Development of Mathematics in the 19th Century
J.E. Littlewood. A Mathematicians Miscellany
G.H. Hardy. A Mathematician’s Apology
R. Courant, H.Robbins. What Is Mathematics?
V.I. Arnold. Mathematical Understanding of Nature: Essays on Amazing Physical Phenomena and Their Understanding by Mathematicians.
What else? The author must be an influent mathematician and the book must not be "just another popular math book".