I should have desired, in the first place, to explain in it what philosophy is, by commencing with the most common matters, as, for example, that the word “philosophy” signifies the study of wisdom, and that by wisdom is to be understood not merely prudence in the management of affairs, but a perfect knowledge of all that man can know, as well for the conduct of his life as for the preservation of his health and the discovery of all the arts, and that knowledge to subserve these ends must necessarily be deduced from first causes; so that in order to study the acquisition of it (which is properly called philosophizing), we must commence with the investigation of those first causes which are called “principles.” Now these principles must possess two conditions