154 
RELATIONS. 
periment of digestion with the gastric juice in vessels, the 
grain must be crushed and bruised before it be submitted 
to the menstruum; that is to say, must undergo by art with¬ 
out the body, the preparatory action which the gizzard ex¬ 
erts upon it within the body; or no digestion will take place. 
So strict, in this case, is the relation betweeen the offices 
assigned to the digestive organ, between the mechanical 
operation, and the chemical process. 
II. The relation of the kidneys to the bladder, and of 
the ureters to both, i. e. of the secreting organ to the ves¬ 
sel receiving the secreted liquor, and the pipe laid from one 
to the other, for the purpose of conveying it from one to 
the other, is as manifest as it is amongst the different ves¬ 
sels employed in a distillery, or in the communications be¬ 
tween them. The animal structure in this case being sim¬ 
ple, and the parts easily separated, it forms an instance of 
correlation which may be presented by dissection to every 
eye, or which indeed, without dissection, is capable of be¬ 
ing apprehended by every understanding. This correla 
tion of instruments to one another fixes intention some¬ 
where: especially when every other solution is negatived 
by the conformation. If the bladder had been merely an 
expansion of the ureter, produced by retention of the fluid, 
Jiere ought to have been a bladder for each ureter. One 
receptacle, fed by two pipes, issuing from different sides of 
the body, yet from both conveying the same fluid, is not 
to be accounted for by any such supposition as this. 
III. Relation of parts to one another accompanies us 
throughout the whole animal economy. Can any relation 
be more simple, yet more convincing, than this, that the 
eyes are so placed as to look in the direction in which the 
legs move and the hands work? It might have happened 
very differently if it had been left to chance. There were 
at least three-quarters of the compass out of four to have 
erred in. Any considerable alteration in the position of 
the eye, or the figure of the joints, would have disturbed 
the line, and destroyed the alliance between the sense and 
the limbs. 
IV. But relation perhaps is never so striking, as when 
it subsists, not between different parts of the same thing, 
but between different things. The relation between a 
lock and a key is more obvious than it is between differ¬ 
ent parts of the lock. A bow was designed for an arrow, 
and an arrow for a bow: and the design is more evident 
for their being separate implements. 
Nor do the works of the Deity want this clearest spe- 
