AND FUNCTIONS OF ANIMALS, &C. 
47 
of nature,) to the wise and well-contrived disposition of 
each muscle for its specific purpose; for moving the joint 
this way, and that way, and the other way; for pulling 
and drawing the part to which it is attached, in a determi¬ 
nate and particular direction; which is a mechanical oper¬ 
ation, exemplified in a multitude of instances. To mention 
only one: The tendon of the trochlear muscle of the eye, 
to the end that it may draw in the line required, is passed 
through a cartilaginous ring, at which it is reverted, exactly 
in the same manner as a rope in a ship is carried over a 
block or round a stay, in order to make it pull in the direction 
which is wanted. [PI. Vl t fig. 1.] All this, as we have 
said, is mechanical; and is accessible to inspection, as ca¬ 
pable of being ascertained, as the mechanism of the au¬ 
tomaton in the Strand. Suppose the automaton to be put in 
motion by a magnet, (which is probable,) it will supply us 
with a comparison very apt for our present purpose. Of 
the magnetic effluvium, we know perhaps as little as we do 
of the nervous fluid. But, magnetic attraction being as¬ 
sumed, (it signifies nothing from what cause it proceeds,) 
we can trace, or there can be pointed out to us, with per¬ 
fect clearness and certainty, the mechanism, viz. the steel 
bars, the wheels, the joints, the wires, by which the motion 
so much admired is communicated to the fingers of the im¬ 
age: and to make any obscurity, or difficulty, or contro¬ 
versy in the doctrine of magnetism, an objection to our 
knowledge or our certainty concerning the contrivance, or 
the marks of contrivance, displayed in the automaton, 
would be exactly the same thing, as it is to make our ig¬ 
norance (which we acknowledge) of the cause of nervous 
agency, or even of the substance and structure of the 
nerves themselves, a ground of question or suspicion as to 
the reasoning which we institute concerning the mechani¬ 
cal part of our frame. That an animal is a machine, is a 
proposition neither correctly true nor wholly false. The 
distinction which we have been discussing will serve to 
show how far the comparison, which this expression im¬ 
plies, holds; and wherein it fails. And whether the dis¬ 
tinction be thought of importance or not, it is certainly of 
importance to remember, that there is neither truth nor 
justice in endeavouring to bring a cloud over our under¬ 
standings, or a distrust into our reasonings upon this sub¬ 
ject, by suggesting that we know nothing of voluntary 
motion, of irritability, of the principle of life, of sensation, 
of animal heat, upon all which the animal functions de¬ 
pend; for, our ignorance of these parts of the animal frame 
