348 RESEARCHES INTO THE CAUSES OF BLINDNESS. 
Part II. Chapter I. 
PRACTICAL OBSERVATIONS ON THE CAUSES OF BLINDNESS. 
“ The problem of the internal nature of diseases can only be solved by an 
intimate acquaintance with the nature and mechanism of pathogenic causes. 
It is, however, unfortunately the fact that, in the present state of science, the 
mechanism of by far the greater part of these causes is enveloped in profound 
darkness, and consequently the same darkness envelopes the actual nature of 
the diseases arising from these causes.” 
Bouillaud' s Essay on Medical Philosophy. 
Of all the etiological researches hitherto made, those which have 
been undertaken with the view of discovering the causes of blind- 
ness, have certainly most arrested the attention of veterinary sur- 
geons and lovers of the horse : nor is this to be wondered at, 
since there is no affection which so completely deteriorates the 
animal in every sense. No sooner has Nature afflicted him with 
this irremoveable infirmity, than in nine cases out of ten he be- 
comes despised even by his master, and drags out a weary life of 
suffering, and neglect. The same cares are no longer lavished on 
him. He is no longer petted, groomed, and well-fed. Any thing 
is good enough for the blind horse. He is hardly worked and often 
badly lodged and fed, if not in every respect ill-treated. His 
strength is over-tasked, his health no longer an object of solicitude ; 
he becomes prematurely worn out ; and yet, often for awhile re- 
sembling nothing but a living skeleton, he retains all the charac- 
teristics of blood, and breeding, and beauty, and moves those to 
take pity on him who think what, but for this fatal disease, he might 
have been. 
In order properly to appreciate the pernicious influences that 
operate in certain localities, slowly but surely, on the greater part 
of animals, it is necessary to commence with certain considera- 
tions : — 
First : What are the predominating breeds and kinds of horses 
in these parts 1 
Secondly : In what manner are they bred, managed, and fed ! 
Thirdly : What is the climate, the soil, and the principal atmo- 
spheric alterations 1 
Fourthly : What is the actual state of agriculture as connected 
with these animals 1 
We will endeavour to shew how all these causes, apparently 
acting in different ways, conspire to produce an infirmity which is 
