The ancient Greek philosopher Aristotle stated that when confronted by two contraries, one is negative in relation to the other. Evil and suffering, being part of matter, are also illusion: the only reality of sin, sickness and death is the awful fact that unrealities seem real to human, erring belief. God, being all-good, wishes to do what is best for humanity and, it is argued, allowing the person total freedom to give in to temptation even if it results in harm will result in that person learning from his actions and is more conducive to the development of moral autonomy. If God is omnipotent then, it is argued, he can do absolutely anything. In the USA, Mary Baker Eddy, the founder of Christian Science, believed in a system of spiritual healing based on the principle that the mind is the only reality, and matter, therefore, is an illusion.