PREFACE ix 



et perficere is a guiding principle which he obeys in all his 

 investigations. This attitude will seek expression in the 

 course of the present treatise. The writer is quite uncon 

 scious of having said or intended anything new or original. 

 But neither has he intended to make a mere compilation. 

 It has been his ambition to assimilate and analyse what he 

 has learned from others ; and, bearing in mind the require 

 ments of beginners, to set forth the results of his own labours 

 in the manner and order he considers most helpful to those 

 for whom he has written. The main body of the doctrine 

 is, of course, derived from the study of Aristotelean 

 and Scholastic authors ; but he wishes here to express his 

 large indebtedness to those recent writers on logic from 

 whose works he has derived much really valuable assist 

 ance. This he hopes he has duly acknowledged through 

 out the work itself. Among the authors he has found most 

 helpful are the following : Mercier (Scholastic), Logique (4th 

 edit, Louvain, 1705); Welton, Manual of Logic (vol. i., 

 2nd edit, London, 1904; vol. ii., London, 1901) ; Keynes, 

 Formal Logic (4th edit., London, 1906) ; Venn, Empirical 

 Logic (London, 1889); J ovce (Scholastic), Principles of 

 Logic (London, 1908) ; and Joseph, An Introduction to 

 Logic (Oxford, 1906). The latter, a remarkably mature 

 and scholarly work, is largely Aristotelean ; and although 

 its positions have not been uniformly accepted in the 

 present work, it has been consulted with uniform profit 

 throughout. The student will be well rewarded for per 

 using it. All those authors have been allowed to speak 

 for themselves wherever the clearness and brevity of their 

 statements surpassed anything to which the present writer 



Vos omnes, Venerabiles Fratres, quam enixe hortamur, ut ad catholicae Fidei 

 tutelam et decus, ad societatis bonum, ad scientiarum omnium incrementum, auream 

 sancti Thomae sapientiam restituatis, et quam latissime propagetis. Sapientiam 

 sancti Thomae dicimus : si quid enim est a doctoribus scholasticis vel nimia eub- 

 tilitate quaesitum, vel parum considerate traditum, si quid cum exploratis posterioris 

 aevi doctrinis minus cohaerens, vel denique quoquo modo non probabile, id nullo 

 pacto in animo est aetati nostrae ad imitandum proponi.&quot; Encyclical Aeterni Pairis 

 of Pope Leo XIII. on Christian Philosophy, August, 1879. 



