Euclid: The Man Who Invented Geometry is an illustrated chapter book that explains the life of the Greek mathematician Euclid, who lived around 300 BC. The focus is on his discoveries in geometry. In ten chapters he is shown explaining his concepts and system to a group of friends. He talks them through his definitions and method, step by step, from “point” to “polygon.” The chapters advance from point and axiom (ch. 1) to angle and parallel (ch. 2). Then kinds of angle and so to the circle (3). Then how to measure angles (4). Triangles get classified and named (5). We move from three- sided to four-sided figures (6), and so to the joys and purposes of bisection (7), with use of geometrical tools like compasses. In the next two chapters the story diversifies, because polygons are many, as are their relationships. And so to the final chapter, on the behaviour of angles in polygons, and how to measure them, and why does a pentagon have 540 degrees. The book ends with a page of gruesome geometry jokes, then tells you how to take the subject further on Rayner’s website (accessed: April 1, 2020).

“Geometry is all about relationships,” p. 5, and Rayner introduces human relationships to support that point through his illustrations of Euclid and his friends. They are not silent, in fact they chirp and chatter, with endearing jokes and puns. After step one, defining line as what joins two points, they say “We get the point.” Later we meet a running gag on isosceles / sausages. The graphics, further, make the exegesis entertaining. The goofy faces and Greek dress of the friends go beautifully with the austerity of the geometric diagrams. The text weaving its way around both makes it all like a story.

So entertainment balances information. As with many children’s textbooks, Rayner is using jokes and cartoons to ease education. The subject is severe and quite exceptionally interconnected: the interpersonal and amusing treatment brings Euclid’s thought-world close to us.

Euclid himself is a brilliant choice. His kind of geometry was taught for the next 2000+ years. Its terminology still surrounds us, and the Greek words too, both familiarly (axiom, triangle) and more technically (trapezium, scalene). This whole topic has so many ways of connecting his thought-world with ours!

Rigour is necessary for it, and we are not only told about logic but the proceeding from axioms is demonstrated. And there is good jam on the pill. The puns all make you groan, and the story-line and graphics enhance the exegesis: we groan, remember, and understand. Any child reading Euclid who has never met geometry before, will now know these basics for ever. Rayner doesn’t thrash the relevance of Euclid, maths, or the Greek language. His touch is light, the thing is fun. Yet here a young reader could fall in love with triangles, as shapes, as a word, an ingredient, or anything else about the world.