What is the reality or fundamental stuff of the universe? With regard to this age-old question, in Western philosophy, there are six worldviews under the main groups called organic worldview, spiritual process worldview, mechanistic worldview, and physical process worldview. These worldviews would logically lead to seven theories of reality (ultimate reality). This innovative framework can give the basic classification of the entire range of diverse philosophical doctrines, including idealism, materialism, and mysticism. An intellectual and secular analysis of the separate streams of philosophy-denoting them together as monistic philosophy-covers the major part of this book. Then, for solving the above controversies, this author discovers system philosophy with the key principle: Ultimate reality is the system of opposite forces called body and consciousness, which are represented by x-axis and y-axis, respectively, of coordinate geometry. Then reality is like a factory, producing worldly things as systems of those opposite components. The final part of this book establishes the existence of seven social systems at the global level into which human life is divided. In this way, we can reconcile the issues of knowledge and truth pertaining to various branches of natural science and social science as well as religion.