Cartesian dualism refers to the mind-body split that the French philosopher René Descartes proposed as the foundation of his worldview. It is one of the main sources of our disconnection from nature, and from our own bodies. Descartes lived in traumatic times: - In 1610, Galileo looked through his telescope and saw that there were moons orbiting Jupiter. He reasoned that not all celestial bodies orbited the Earth, and therefore Copernicus' heliocentric model of the cosmos was probably right. This had a destabilising effect on all those who had been accustomed to think of the Earth as the centre of a womblike cosmos. - In 1618, the Thirty Years War began as a civil war with the Holy Roman Empire. By the time it ended in 1648, it had drawn in the rest of Europe and claimed 8 million lives. In 1619, Descartes had a series of dreams that would set him on his path of philosophical scepticism. Descartes was highly infuential on the course of the European Enlightenment, and we are now living the consequences of that influence. He combined algebra, arithmetic and geometry into algebraic geometry, and enabled the quantification of space.