Mathematics of the Soul: Numbers, Light, Memory, and the Teachers Who Never Leave Us

Before mathematics became equations it was a wonder, and this book follows that wonder through the people who gave it form: Euclid, who built a cathedral of reasoning in place of stone, Pythagoras, who heard harmony in a vibrating string, al-Khwarizmi in Baghdad, whose work gave algebra its name, and Ibn al-Haytham, who brought geometry to light and vision. As an architect the narrator cannot separate mathematics from space, since before the column carries stone mathematics carries the column, and he follows the subject into stranger landscapes with Maryam Mirzakhani and her surfaces bending toward infinity. Then memory returns him to a classroom, a blackboard and his teacher Mahmoud Hamsho, whose sentence, that he might fail to solve a problem yet would never solve it wrongly, the narrator once heard as mathematics and now hears as ethics: do not invent the answer, and if you do not know, say so. The book writes the equations no school teaches, such as knowledge plus humility equals wisdom, and gathers all these masters at a last blackboard beneath the stars, where the teacher writes his sentence beneath their equations. It ends with peace upon the masters and the conviction that mathematics taught us how to calculate, while our teachers taught us how to live.