This is a relatively short treatise by the highly influential and admired philosopher and polymath Leibniz. It presents his views on metaphysics including the role of God in providing universal optimisation and order, along with the role and definition of individual substances including spirits, and the relation of the soul to the material body. He relates his views to those of foregoing scholastic philosophers and to Plato himself. There is discussion of free will and sin vis-a-vis God's omniscience. In a reference to laws of physics he is critical of Descartes. He discusses the importance of final causes and efficient causes in regard to mechanics. He also discusses the nature and origin of knowledge. He concludes by asserting the place of Christ in promulgating the city of God and the monarchy of heaven. (Summary by Peter Tucker)