A Comet of the Enlightenment, authored by Johan C.-E. Stén, is the first full biography of Anders Johan Lexell (1740–1784), an exceptionally gifted Finnish mathematician and astronomer. Stén does a masterful job of showing us not only Lexell the person, but also how Lexell’s professional life and choices were influenced by the political and academic cultures of his day. The biography tells of Lexell’s formative years growing up in Sweden, his early attempts at establishing a professional life that led him to Saint Petersburg, his two-year journey of Europe, and his return to the Petersburg Academy of Sciences.
In his research, Stén read copious letters of correspondence most written by Lexell, academic papers produced by Lexell, and minutes from meetings of the Petersburg Academy of Sciences. History of Mathematics enthusiasts will appreciate the infusion of primary source excerpts in the book which provide credibility, evidence, and richness to the story.
Lexell wrote at least 112 letters to Pehr Wargentin, Secretary of the Royal Academy of Sciences in Stockholm, and it is through these letters that we learn most about Lexell. Especially notable are the letters written during his tour of Germany, France, and England amidst the enlightenment. Lexell describes the people he meets, the architecture of the cities in which he resides, and the sights and activities in which he takes delight.
Minutes from the Petersburg Academy reveal the contentiousness that existed in academia as well as the high expectations for members. However, for Lexell, Saint Petersburg was a destination of choice where he could pursue his astronomical and mathematical researches. And it offered him the opportunity to be an assistant, an associate, and friend to the esteemed Leonhard Euler. Euler expressed confidence in Lexell’s opinion and judgment and Lexell “became known as Euler’s closest associate and one of the few at the time who could actually understand his reasoning.”
In his brief life, only 43 years, Lexell produced over a hundred publications. Stén’s explication of Lexell’s studies in astronomy and mathematics is admirable, providing enough detail to understand the questions and problems Lexell undertook. Readers can appreciate the breadth of work and contributions made to the body of knowledge in both disciplines. Students looking for a research focus would do well to read these chapters as there are a number of problems, questions, and names mentioned that may be worthy of investigation.
Readers of A Comet of the Enlightenment will learn a lot about Lexell and even more about the enlightened culture in which he lived.
Cindia Davis Stewart is an Associate Professor of Mathematics at Shenandoah University in Winchester, Virginia.