Remarkable polymath though he was, Pavel Florensky should not, perhaps, be compared to Leonardo da Vinci. For one thing, he had no patron: Stalin, unlike Cesare Borgia or King Francis I, preferred to annihilate any polymath who threatened his own monopoly on genius. For another, however skilled he was in his laboratory with his hands, Florensky was primarily a theologian and a mathematician, and only secondarily a geologist, electrical engineer, chemist and inventor. And, unlike da Vinci, Florensky was both a saintly man with serious claims to canonisation and a family man whose example enabled his widow and sons to survive the horrors of Stalinism.

Any student, or biographer, of Pavel Florensky has two hurdles to surmount. Mathematics progresses from easy a priori assumptions, such as 1 + 1 = 2, to bewildering multi-dimensional non-Euclidean space; theology ends with the easily accepted ‘We must love one another, or die’ only by starting with