Professor Play fair on Mathematical and Physical Science. 587 



•ould not fail to suggest, as a farther con- 

 sequence, that every perception of the 

 mind is the immediate effect of the divine 

 ' illumination. As to the manner in which 

 this illumination is accomplished, the 

 extraordinary hypothesis adopted by 

 Malebranche was forced upon him by the 

 opinion then universally held, that the 

 innnediate objects of our peiceptions are 

 not things external, but their ideas or 

 images. The only possible expedient 

 for reconciling these two articles of his 

 creed, was to transfer the seat of our 

 ideas from our own minds to (hat of the 

 Creator. 



BISHOP BERKELEY. 



From the indissoluble union between 

 the notions of colour and of extension. 

 Dr. Berkeley has drawn a curious and, 

 in my opinion, most illogical argument in 

 favour of his scheme of xiealism ; which, 

 as it may throw some additional liglit on 

 the phenomena in question, I shall tran- 

 scribe in his own words. 



" Perhaps, upon a strict inquiry, we 

 shall not find that even those who from 

 their birth have grown up in a continued 

 habit of seeing, are still irrevocably pre- 

 judiced on the other side, to wit, in 

 thinking what they see to be at a distance 

 from them. For, at this time, it seems 

 agreed on ail hands, that colours, which 

 are the proper and immediate objects of 

 siglit, are not without the mind. But 

 then, it will be said, by sight we have 

 also the ideas of extension, ;ind figure, 

 and motion ; all which may vvell be 

 thought witkout, and at some distance 

 from the mind, though colour should not. 

 In answer to this, I appeal to any man's 

 experience, whether the visible extension 

 of any object doth not appear as near to 

 him as the colour of that object ; nay, 

 whether they do not both seem to be in 

 the same place. Is not the extension 

 we see coloured ; and is it possible for 

 us, so much as in thought, to separate 

 and abstract colour from extension? 

 Now, where the extension is, there surely 

 is the figure, and there the motion too. 

 I speak of those which are perceived by 

 sight." 



Among the multitude of argumrnts 

 Rd»anced by Berkeley in support of iiis 

 favourite theoi^-, I do not recollect any 

 that strikes me more with the appear- 

 ance of a "ilful sophism than the fore- 

 going. It is dithciilt t ) conceive how so 

 very acute a reasoner should not have 

 perceived that his pienil>es, in this in> 

 stance, lead to a conclubion directly op- 

 posice to uli«t he has drawn from them, 

 Siipposinv all niunkind to have an ice- 

 MuMttLv Mag. Nj. '293. 



sistible conviction of ?he outness and 

 distance of exieiiiion and figure, it is 

 very easy to explain, f'nnn the association 

 of ideas, and from our early habits of 

 inattention ta-i4re phenomena of consci- 

 ousness, how. the sensations of colour 

 should appear to the imagination to be 

 transported oiit of the iniMil. But if, 

 according to Berkeley's doctrines, the 

 constitutKJii of luinnin nature leads men 

 to believe that extension and fifj,urc, and 

 every other quality of the lOHterial uiiii 

 verse, exists only within themselves, 

 whence the ideas of external and of j«- 

 ternat ; of remote, or oi near ^ When 

 Berkeley says, " I appeal to :iny m.io% 

 experience, whether the visible extension 

 of any object doth not appear as near t« 

 him as the colour of that object," iiovr 

 much more reasonable would it have been 

 to have stated the indisputable fact, 

 that the colour of the object appears us 

 remote as its extension aod figure ? No- 

 thing, in my opinion, can alfoid a more 

 conclusive proof tbat the natural judg- 

 ment of the mind is against the inference 

 just quoted from Berkeley, titan the 

 problem of D'Aleinljert, which has given 

 occasion to this discussion. 



PROrESSOR Playfa(r's Histori) of the 

 Frosivtss of Malhe/nalicul and HJii/'Sf^ 

 cat Science, since the Revival {^ Letters 

 in Europe. 



GEOMETRICAL ANALYSTS. 



Another great invention, the Geomp- 

 trical Analysis, ascribed very genera. ly 

 to the Platonic school, but moit succe;s- 

 fuily ctiltivaieii by Apillonius, is one of 

 the most ingenious and beautiful con- 

 trivances in the inatheinacics. It is a 

 method of discovering truth by reasoning 

 concerning things unknown, or propo- 

 sitions merely supposed, as if tlie one 

 were given, or the other were really uue, 

 A quantity that is unknown, is only to lie 

 found from the relations which it beirs to 

 quantities tli;<t are known. By rea-ioniiig 

 on these relations, we come at last to 

 some one so siinple, that the thing sought 

 is iheieby dctornnried. By liiis analyti.- 

 ca! process, ihertfore, the thing requited 

 is discovered, and we aro ttt the saina 

 time put in possession of an instrument 

 by which new truths m.iy be found out, 

 and wiiicli, wiicn sk.ll in using it hot been 

 acquired by [iractice, may be ajiplied to 

 an unliniiied extiMU. A siiininr process 

 enables us to rlibcover the dtmonstraiionj 

 of propositions, sup^iosed to he true, or, 

 if not trun, to discover th.ii they are falar. 



Tins method, to the coosnieration of 



which we iihaU tigain have aihv.ipo>'Cunity 



4. r * ci 



