Ontology or the Theory of Being
Hence we arrive at this simple and widely accepted definition of philosophy: the science of all things through their ultimate reasons and causes as discovered by the unaided light of human reason.(5) The first part of this definition marks off philosophy from the special sciences, the second part marks it off from supernatural theology.
We must remember, however, that these three departments of knowledge--scientific, philosophical, and revealed--are not isolated from one another in any man's mind; they overlap in their subject-matter, and though differing in their respective standpoints they permeate one another through and through. The separation of the special sciences from philosophy, though adumbrated in the speculations of ancient times and made more definite in the middle ages, was completed only in modern times through the growth and progress of the special sciences themselves. The line of demarcation between philosop