HAVING for many years openly defended the Philosophy of St. Thomas, even in what concerns the fundamental doctrines of organic and inorganic nature, we think it time to treat that subject, not merely touching on one or another point, but dealing with those doctrines philosophically. These and other reasons have induced us to put before our readers, especially those who are given to the study of philosophy and natural sciences, that system which we call the Physical System, whose principles were certainly professed by the Angelic Doctor, St. Thomas. It is, or should be, unnecessary to say that we are not going to rake up exploded doctrines of the old physicists. The habit of confusing such opinions with the philosophical principles of rational Physics, ascribing to the latter what belongs to pure experiment, has led many to attack truth with the hatred due to error and to put the wisest in the category of quacks.