1881.] The Inconceivable as a Test of Truth . 145 
potabie. But they are also met with in pools fed by the 
surface drainage of manured fields and pasture lands. As a 
rule it may be said that animals which prey upon living 
animals or growing vegetables are not, in themselves, a bad 
symptom. All such as consume dead, comminuted, or putres- 
cent matter, whether animal or vegetable, must be con- 
sidered highly objectionable, as proving the presence of the 
bodies upon which they feed. 
We may, therefore, probably conclude that neither vege- 
table nor animal life varies in any single relation with the 
proportion of oxygen found in a stream ; that sewage fungus 
and all aquatic growths devoid of chlorophyll, where existing 
alone, indicate great pollution; but that where they occur 
along with green plants the impurities may be very trifling. 
Yet even vegetation of a relatively high grade, such as the 
water-cress, gives no positive proof that a stream is whole- 
some and potable. Lastly, it is impossible to argue from 
ordinary town-sewage to manufaCturing-refuse, or to a 
mixture of the two. The influence of the former upon 
animal and vegetable life is widely distinct from that of the 
latter. 
IV. THE INCONCEIVABLE AS A TEST OF 
TRUTH. 
By F. H. Nash. 
S HAT all our knowledge is subjective is now looked on 
by a large number of those who think on such matters 
as a proposition proved. That this is equivalent to 
saying that knowledge in the true sense of the word is not 
to be attained by us at all, is at least to “ our present reason” 
evident. That the same proposition logically involves 
general scepticism is not, however, my reason for calling it 
or its alleged proofs in question. If it be true let it stand, 
“ Fiat justitia mat ccelum .” Locke was no sceptic, yet his 
system, which referred all our ideas to experience, neces- 
sarily led to scepticism. Kant did not love scepticism, he 
desired to set up a barrier against it ; yet he is supposed to 
have completely established the doCtrine of the subjectivity 
of our knowledge, and may therefore be considered the 
father of such modern scepticism as deserves the name of 
