552 . ox THE EXTERNAL CAUSES OF DISEASE. 
and general experience with which it can be furnished, so as to 
build up a more harmonious and consistent philosophy than w^e 
at present enjoy, the facts themselves, and our general experi¬ 
ence, must be of that definite and indisputable kind that will im¬ 
press on our minds a conviction of their immutability. 
The differences of opinion that have existed and still exist in 
the forms and modes of practice among medical practitioners is 
astonishing: they are constantly changing ; for what man is 
pleased to term the perfection of the science to-day, is by ano¬ 
ther, to-morrow, deemed comparative ignorance. Discrepancy 
of opinion in matters of faith may be easily allowed, because there 
is no common measure of the subject of disputation by which 
these disputes may be adjusted—one man’s faith can swal¬ 
low a camel, whilst another’s is scarce equal to the digestion of 
a sparrow.” But in the sciences, where we have observation and 
experience as guides, it is, we repeat, astonishing that such dif¬ 
ferences should exist. 
In these disputes too, that trite and excellent adage —In 
medio tutissimus ibis” is altogether forgotten : 
“ One to the right, one to the left recedes, 
Alike deluded, as each fancy leads.” 
These remarks are occasioned in consequence of observing the 
great differences of opinion that exist respecting the nature and 
properties of the blood: one party endeavouring to find in the 
changes undergone by the blood and the other fluids the cause 
of all diseases, whilst another, determined solidists,” maintain 
that all diseases arise from a deranged condition of the solids, 
and that every change in the condition of the fluids is a conse- 
quence of that derangement. 
“ Felix qiii potuit reruni cognoscere causas.” 
The believers in the humoral pathology were in error in attri¬ 
buting all diseases to a defect of the humours; and the so- 
lidists” have been equally in the wrong, in saying that a primi¬ 
tive change in the condition of the fluids is imaginary, and that 
the doctrine of humoral pathology is without foundation. Pro¬ 
fessor Coleman was the first who placed this matter of dispute 
in the clearest point of view, when by his simple, yet celebrated 
