280 



Mk DE morgan, on the syllogism, No. Ill, &o. 



obtains 612 possible moods, of which all but 36 are 

 rejected as either useless or invalid. Some one, I know 

 not who, or how, obtained 9210 moods. This I learn 

 from an old disputation, de Arte Syllogiatica, held at 

 Leipsic in 1675, in which the young respondent, 

 Christian Ihlius, after alluding to the 612 and the 

 9210, proceeds thus: — Verum hi ipsi peccant turn in 

 Deum turn in proximum: in Demn, drmfi^dona concessa 

 tarn male impendunt; in proximum, dum ingenia dis- 

 centivjm magis onerant quam juvant. 



Leibnitz himself worked out the 912 moods so soon 

 as he saw Hospinian's title-page, and has given his 



account of them in the dissertation I have been citing. 

 It is de Arte Comhinatoria, first published at Leipsic 

 in 1666, when Leibnitz was twenty years old. He ap- 

 proves of Hospinian's syllogisms of weakened conclu- 

 sion, but attacks his treatment of the singular pro- 

 position as particular : Titio omnes vestes quas habeo do 

 lego, quia dubitet etsi unicam habeam ei deberi f Wallis 

 had maintained the same in a disputation at Em- 

 manuel College in 1631, being then not sixteen years 

 old. Leibnitz's dissertation de Arte Combinatoria must 

 have been written as a university thesis, whether so 

 read or not. 



June 25, 1858. 



