Both modern philosophy and modern mathematics began with the work of Rene Descartes. The universe is basically composed of two elements, matter and mind. All philosophical assumptions can be challenged on the ground that it is impossible to prove that there can be any real knowledge of the world.
Reality is essentially mental or spiritual.
The material world is a lesser order of reality. In its most extreme form materialism is the belief that all of reality consists solely of matter. It denies the existence of spirits, souls, and gods, and it insists that all activities of mind and emotion are based on physical properties. Throughout its long history, materialism has been closely associated with, and supported by, investigations into the physical sciences. These sciences have long been based only on studies of matter, of physical bodies and their properties.