Philosophy in the present book is considered as a discipline which consists of the branches ontology, epistemology and axiology. In the beginning of each chapter, a short introduction has been written about the personality and biography of the two (or four) philosophers investigaed in that chapter. Philosophers studied and compared in this book are as follows: Tusi and Aristotle, Ghazali and Aquinas, Ibn Miskawayh and Aquinas, Farabi and Spinoza, Ibn Sina and Edwards, and Rumi, Sa'di and Rousseau, Dewey.
