Vlil 



In the coarse of these speculations, and others of a hke nature which 

 grew out of them, Mr. Boole was led to consider the possibility of con- 

 structing a calculus of deductive reasoning. The severe disciphne of his 

 efforts to extend the powers of the analysis had given him not only a com- 

 plete mastery over its mechanical processes, but also, what was of far 

 greater advantage, a profound insight into its logical principles. In tracing 

 out those principles he discovered that they admitted of an application to 

 other objects of thought than number and quantity ; he found, in fact, 

 that logical symbols in general conform to the same fundamental laws 

 which govern the symbols of algebra in particular, while they are subject 

 also to a certain special law. This discovery suggested a variety of in- 

 quiries which he seems at different periods to have pursued, but without 

 any intention of publishing his views on the subject. In the spring of the 

 year 1847, however, his attention was drawn to the question then moved be- 

 tween SirW. Hamilton of Edinburgh and Professor De Morgan, and he ''was 

 induced by the interest vv^hich it inspired, to resume the almost forgotten 

 thread of former inquiries." His views were embodied in a remarkable essay, 

 entitled ''The Mathematical Analysis of Logic," which in the autumn of 

 the year was put on sale in Cambridge and London. Early in the follow- 

 ing year (1848) he communicated to the Cambridge and Dublin Mathe- 

 matical Journal a paper on the "Calculus of Logic," in which, after 

 premising the notation and fundamxcntal positions of his essay, he gave 

 some further developments of his system. From this time forward he 

 applied himself diligently to a course of study and reflection on psycholo- 

 gical subjects, with a view to the production of a much more elaborate and 

 exhaustive work than either of those above named. He felt that the 

 inquiry was one of great importance, and that in labouring to perfect his 

 theory he was rendering essential service to science. He meditated deeply 

 on the nature and constitution of the human intellect. The most eminent 

 authorities, both ancient and modern, were consulted ; opinions differing 

 widely from each other, and often wholly opposed to his own, were care- 

 fully considered ; and whatever was likely to help him in the great work 

 which he had undertaken, was eagerly sought. Mental science became 

 his study ; mathematics were his recreation. So he has been heard to 

 say ; and yet it is a remarkable fact, and one which serves to show the 

 great power and genius of the man, that his most valuable and important 

 mathematical works were produced after he had commenced his psycho- 

 logical investigations. 



In 1849 he was appointed to the Mathematical Chair in the newly formed 

 Queen's College at Cork ; and when the Queen's Colleges of Belfast, 

 Gal way, and Cork were united so as to form the Queen's University of 

 Ireland, he was chosen one of the public examiners for degrees. These, 

 offices he filled with the highest reputation. In 1852 the University of 

 Dublin conferred upon him the honorary title of LL.D., in company with 



