I reckon the book gives a very good measure of Sir Isaac Newton's interests in philosophy. One shoulk ask why philosophy? Well we have to say that this writings contain some of the best arguments ever used in defense of God's existence. Moreover, the "Four letters to Mr. Richard Bentley" contain what should be considered the argument of "imperfection" for the existence of a Voluntary Agent in the Universe. Nobody before Newton dared to say that from the imperfection of this world it follows that God neccessarily exists. This argument will be, of course, a great subject for the criticism of Leibniz and Descartes' disciples. Then again, the book contains a very good paper on the natural and un-natural motion of celestial bodies, a very good treatise in itself on inertia and gravity, which makes us wonder whether our modern view on the universe is a Newtonian or a Cartesian one. After all the theme is very actual and it has not lost it's strenght.