Gösta Mittag-Leffler (1846–1927)
promoter, mentor, correspondent and friend
He was a Swedish mathematician, who founded the journal Acta Mathematica and the Mathematics Institute of the Swedish Academy of Sciences that bears his name. He promoted Sofia's academic position in Stockholm and invited her to the editorial board of the Acta Mathematica.
What most deeply interested me in St Petersburg was getting to know Madame Kovalewsky. Today [10 February 1876] I spent several hours at her house. As a woman, she is delightful. She is beautiful and when she speaks, her face illuminates with such an expression of feminine kindness and superior intelligence, that the effect is dazzling. Her manner is simple and natural without the slightest trace of pedantry or pretence. She is in all respects a complete ‘woman of the high world’. As a scholar she is characterized by her unusual clarity and precision of expression. The depth of her knowledge becomes clear then and I understand fully why Weierstrass considers her the most gifted of his students. [Weierstrass et Sonja Kowalewsky, 172]