Iranian-born mathematician Maryam Mirzakhani, the first woman to win the Fields Medal, has died at the age of 40 after a long battle with cancer. Mirzakhani's death was announced on Instagram on Saturday by her friend Firouz Naderi, who lamented that “a light was turned off today.” “It breaks my heart…gone far too soon,” he wrote. Mirzakhani, a professor at Stanford University, had been fighting cancer for four years before it finally spread to her bone marrow. She was lauded as a trailblazer for women in mathematics after receiving the Fields Medal in 2014, the highest honor in the math world. Although she resided in the U.S., Mirzakhani was highly respected back in Iran, where President Hassan Rouhani reacted to her passing on Saturday with a statement praising her “unprecedented brilliance” and expressing his “great sorrow” at her death.