Handbook of Greek Philosophy is a real guide for anyone who wants to know about Ancient Greek philosophy, but he does not know how to start. Since there are thousands of writings about it, the one who is eager to be informed of Greek philosophy, is all at sea. With the present study one can be gradually initiated into the main principles of the great philosophers, whose thought is the basis of the modern philosophical thought. Due to chronological presentation of the fifteen Greek philosophical schools, the reader can gradually get to the understanding of the philosophical terms and concepts, beginning with the simple (of Thales, Anaximander etc..) and proceeding to the most complex ones (Plato, Aristotle etc..). The original fragments, which have been carefully selected out of thousands, along with their thorough analysis, can enable the reader to fathom the reasoning of the Greek thinkers, and acquire a deep comprehension of their Gnoseology (Epistemology), Ontology and Ethics. With this substantial work of scholarship, both the student and the teacher of philosophy alike can find useful concepts, ideas and quotations, so as to broaden their knowledge and views of philosophy. Apart from that, this essay can help them to make a further inquiry concerning Ontology and Ethics of Greek Philosophy.