For many people understanding the place of mind in nature is the greatest philosophical problem. Mind is often thought to be the last domain that stubbornly resists scientific understanding, and philosophers differ over whether they find that a cause for celebration or scandal. The mind-body problem in the modern era was given its definitive shape by Descartes, although the dualism that he espoused is far more widespread and far older, occurring in some form wherever there is a religious or philosophical tradition whereby the soul may have an existence apart from the body. While most modern philosophies of mind would reject the imaginings that lead us to think that this makes sense, there is no consensus over the best way to integrate our understanding of people as bearers of physical properties on the one hand and as subjects of mental lives on the other. See also consciousness, epiphenomenalism, functionalism, perception, occasionalism, physicalism.