Baruch Spinoza was a 17th century Dutch philosopher who developed a metaphysical system that viewed reality as a single substance with both mind and matter as attributes of God or Nature. He believed ideas correspond perfectly to reality similar to mathematics. Spinoza argued there is only one substance which is God or Nature, and all things in the natural universe are modifications of this single substance. His philosophy was considered radical for the time as he denied personality and consciousness to God, instead viewing God as an impersonal order of nature. Spinoza's works were published after his death due to fears of censorship during his life.