On September 26, 1889, German philosopher Martin Heidegger was born. He is best known for his existential and phenomenological explorations of the "question of Being". His best known book, Being and Time, is considered one of the most important philosophical works of the 20th century.
On August 17, 1586, German theologian, author, and mathematician Johann Valentin Andreae was born. He claimed to be the author of the Chymische Hochzeit Christiani Rosencreutz anno 1459 (1616, Strasbourg, the Chymical Wedding of Christian Rosenkreutz), one of the three founding works of Rosicrucianism, a philosophical secret society said to have been founded in late medieval Germany by Christian Rosenkreutz. Rosicrucianism holds a doctrine or theology "built on esoteric truths of the ancient past", which, "concealed from the average man, provide insight into nature, the physical universe and the spiritual realm."
On August 11, 1464, German philosopher, theologian, jurist, and astronomer Nikolaus of Cusa (in latin: Nicolaus Cusanus) passed away. He is considered as one of the first German proponents of Renaissance humanism. His best known work is entiteled 'De Docta Ignorantia' (Of the Learned Ignorance), where also most of his mathematical ideas were developed, as e.g. the trial of squaring the circle or calculating the circumference of a circle from its radius.
On July 13, 1527, Welsh mathematician, astronomer, astrologer, occultist, navigator, imperialist and consultant to Queen Elizabeth I, John Dee was born. He is considered one of the most learned men of his age. Besides being an ardent promoter of mathematics and a respected astronomer, in his later years he immersed himself in the worlds of magic, astrology and Hermetic philosophy. One of his aims was attempting to commune with angels in order to learn the universal language of creation.