GEORGE BOOLE. 165 



else should turn the page over ; for, unphilosophical as it may 1847. 



be, the touch of the paper periodically intervening is a snake in Berkeley's 



the grass an unphilosophical snake. It is hard to make philo- p L 

 sophers of the fingers. 



No doubt it would favour Berkeley's scheme if no 

 appeal to the external, through the senses, were possible 

 to his reader. But surely this would be giving him more 

 than a fair chance. Another interleaved note : 



Personal identity is what every one has a clear conception of 

 until he reads physiology and metaphysics. In that process he 

 learns that the knife sometimes (gradually) gets a new handle, 

 and sometimes a new blade, and all his notions of identity 

 vanish, with nothing but memory left to puzzle him. ' Mais 

 quand je me tate, et quand je me rappelle, il me semble que je 

 suis moi.' 



If physiology teaches that we are automatic, it ought 

 to find a new nam'e for the nightingale and chess-player, 

 which can be wound up when they have run down. 



Dr. George Boole, 1 author of The Laws of Thought, had 

 introduced himself in the year 1842 to Mr. De Morgan by 

 a letter on the Differential and Integral Calculus, then 

 recently published. His character and pursuits were in 

 many points like those of the author, who found great 

 pleasure in his correspondence and friendship. He was a 

 Mathematician as well as a profound and original stadent 

 of Logic and Metaphysics. In 1839, the same year in 

 which the First Notions of Logic appeared, he had sent hia 

 Mathematical paper, Researches into the Theory of Ana- 

 lytical Transfer, to the Cambridge Philosophical Journal, 

 and in 1844 received the gold medal of the Royal Society 

 for a paper On a General Method in Analysis. In the 

 course of these speculations he was led to consider the 

 possibility of constructing a calculus of deductive reason- 

 ing; and he found that logical symbols conform to the 

 same fundamental laws which govern algebraical symbols, 

 while they are subject also to a special law. * Mental 



1 Professor of Mathematics in Cork College. 



