SEXTUS EMPIRICUS. THE PYRRHONISTS. 281 



criterion, and all demonstration, by which the existence of such a 

 criterion is to be shown, requires itself another demonstration, and so 

 on for ever. We cannot trust our senses they deceive us ; we cannot 

 confide in advisers they differ. And here it may be remarked, that 

 the cavils of Sextus are not, like the dexterous subtilties of Bayle, 

 adroitly insinuated in some lively anecdote, curiously wrought into 

 some brilliant train of reasoning, and unexpectedly introduced in 

 various historical articles which in themselves possess intense in- 

 terest ; but they are methodically and heavily brought out, with 

 tedious and insipid repetition. He argues, that there is no such 

 thing as a demonstration, because it would consist of connected 

 propositions, and this connexion can never be proved. The Stoic 

 objected with great acuteness, You must allow that there may be 

 a demonstration, if you can, as well as if you cannot, prove the 

 contrary : if you cannot, you have no right to deny it ; and if you 

 can, your reasoning is a demonstration. All the Sceptic could answer 

 was, that maxims which destroy others destroyed themselves also ; 

 that the medicine passed away with the disease which it removed. 1 

 He felt that the maxim, " all is false, " is self-contradictory ; for if 

 it be true, all is not false. Sextus proceeds to attack syllogisms a 

 mode of reasoning unquestionably liable to objection, and after- 

 wards produces the following cavil against definitions : " Either you Definitions, 

 know what you are defining, before you define it, or you do not ; if 

 you do not, you cannot define ; if you do, you need not : but, you will 

 answer, I define for the use of others ; but if you understood the point 

 without a definition, why should not they ?"' As if a definition were 

 not the result of a gradual succession of ideas, linked together and 

 developed in a manner useful to ourselves by the simplification, and, 

 for the same reason, still more useful to others. He objects, that a 

 definition, in consequence of the limited nature of our knowledge, may 

 perhaps never embrace all the qualities of the subject; but such 

 reasoning would rather tend to show it to be incomplete, than 

 dangerously false. He objects also, that wrong definitions have been 

 often given ; but does it follow that none are true ? is it because some 

 men have defined light to be the act of a luminous body, that no 

 definition of light can ever be given ? 



After having next examined the various divisions of logic, he devotes Existence of 

 his third book to the consideration of physics, and begins with its the Deity * 

 most important branch, the existence of the Deity premising, how- 

 ever, that in practice he conformed to the established religion, and 

 admitted the necessity of worshipping the gods. And it is fortunate 

 for the happiness of mankind, that the arguments by which he en- 

 deavours to contradict the voice of universal nature are as feeble as 

 they are trite : they are derived from the impossibility of comprehend- 

 ing his essence ; of forming any defined idea of his substance ; and 

 from the diversity of opinions respecting his form and nature. And 

 1 Sext. c. Mathem.; Aristocl. ap. Euseb.; Diog. Laert. lib. ix. sec. 76. 



