Short answers, pulled from the story.
Pavel Florensky was a Russian Orthodox priest, theologian, philosopher, mathematician, physicist, and electrical engineer who died on the 8th of December 1937. He is known for his major theological work The Pillar and Ground of the Truth, his contributions to the Russian Symbolism movement, and his research in mathematics and electrodynamics under the Soviet government.
Florensky was arrested on the 26th of February 1933, accused of conspiring to overthrow the Soviet state and install a fascist monarchy with Nazi assistance. He was sentenced under Article 58 of Stalin's criminal code, with his monograph on the theory of relativity classified as anti-Soviet agitation material.
Florensky's central philosophical work was The Pillar and Ground of the Truth: an Essay in Orthodox Theodicy in Twelve Letters. Most of the book was written during his studies at the Ecclesiastical Academy in Sergiyev Posad, but the complete work was not published until 1914.
Florensky was shot dead on the night of the 8th of December 1937 in a wood near Leningrad, after an extrajudicial NKVD troika sentenced him to death on the 25th of November 1937. According to Antonio Maccioni, he was executed at the Rzhevsky Artillery Range near Toksovo and buried in a secret mass grave in Koirankangas alongside some 30,000 others.
Florensky wrote the essay "Reverse Perspective" in 1919, examining spatial organization in the Russian icon tradition and contrasting it with the spatial conventions of Renaissance art. The essay drew on Oskar Wulff's 1907 work and has remained a foundational text in the field since its publication.
Florensky's name was entered in the list of New Martyrs and Confessors in 1982. Statements later appeared suggesting the Russian Orthodox Church had recognized him as a saint, but it was subsequently clarified that no such formal decision had been made.