As summer runs its natural course back to the first days of the school year, we can’t help thinking about that most demanding of studies: mathematics. It’s safe to say we’re living in a correspondingly geeky time -- high school math tournaments have earned sports-style fanaticism and regular math columns have popped up at large news outlets like the Huffington Post and the New York Times -- which leaves us wondering about the people who have spent lifetimes shaping this notoriously elusive and tantalizing subject.

Love it or hate it, math has proven itself an enduring method for taking in the world around us. The stories of the five mathematicians below are guides through the world of head-spinning wonder and bewilderment that fill even the greatest mathematical minds at the beginning of each math quest, and keep them working, sometimes for years, until they finally come to rest on an underlying system -- one as deep, simple, and elegant as 1 + 1.

"Isaac Newton" by James Gleick

Eighteenth-century British mathematician Isaac Newton sits beside Einstein in popular science imagination. Cast as the inventor of calculus (a feat for which he actually shares a spot with German philosopher Gottfried Wilhelm Leibniz), Newton also first posited the theory of gravity which came to him, legend has it, when a falling apple from a tree he rested beneath hit him on the head. Science writer Gleick draws on his own renowned talents to give both a brilliant character study of the often over-simplified Newton and easy-to-follow exposition on the mathematician’s work, plus that of Aristotle and Gallileo which served as Newton’s foundation.

"Man of Numbers: Fibonacci’s Arithmetic Revolution" by Keith Devlin

At the very beginning of the thirteenth century, “Liber abbaci,” a book by a man named Leonardo da Pisa --and later known as “Fibonacci,” after one of his book’s exercises -- introduced Europe to what we now know as arithmetic and paved the way for the Renaissance’s trade and science era. In this well-rounded account, Devlin, NPR’s Math Guy and math writer for the masses, explores the elusive mathematician’s travels to North Africa, his learning the Hindu number system in use there, and his careful compiling of that Eastern knowledge into a book that would reshape the Western world.

"The Calculus of Friendship" by Steven Strogatz

For more than thirty years Strogatz and his high school calculus teacher wrote to each other about math -- and details of the other parts of life going on around them. Their shared love of calculus stands as the one constant during the ups and downs of a lifetime: losing a parent, the death of a son, an Ivy League professorship, divorce, retirement, and professional kayaking were all documented in the letters that formed and sustained this unusual friendship. Numerous, yet fragmented and filled with the omissions that occur in all human communication, the letters are a personal and heartfelt guide through the continuous field of calculus (complete with gently explained math notation) and the far less smooth paths of two men’s lives.

"Perfect Rigor" by Masha Gessen

In 2006, a Russian mathematician named Grigory Perelman found the solution to the Poincare Conjecture, one of the world’s seven great unsolved math problems, winning the million dollar prize attached to it. He then quickly refused the money and retired from the world of mathematical research. Gessen, once a math student in Russia as well, wrote her book on the press-shy Perelman based on interviews with his family, friends, and associates. Her look at the little understood numbers-counting genius -- whose gift lay not in radical inventiveness but in superhuman precision and rigorous computation -- includes very little math, but plenty of insight into Perelman’s inner workings, plus background on the lives and thoughts of his intellectual predecessors, including Henri Poincare, Bernhard Riemann, and Euclid.

"Prime Obsession" by John Derbyshire

In 1859, mathematician Bernhard Riemann made a hypothesis based on the behavior of prime numbers -- those digits divisible only by themselves and the number one. Known as the Riemann hypothesis, the problem he posed remains unsolved to this day. In this mathematical mystery for lay people, Derbyshire catches the rest of us up to speed with clear explanations of the math involved, a history of the centuries of thought surrounding the hypothesis and a detailed life story of this prolific mathematician whose work straddled both the world of numbers and the world of calculus.