REGARDED AS A MASS 
119 
weakness, the patient cannot stand upright. Secondly, 
that these actions are only in a small degree voluntary. A 
man is seldom conscious of his voluntary powers in keep¬ 
ing himself upon his legs. A child learning to walk is the 
greatest posture-master in the world; but art, if it may be 
so called, sinks into habit; and he is soon able to poise 
himself in a great variety of attitudes, without being sen¬ 
sible either of caution or effort. But still there must be 
an aptitude of parts, upon which habit can thus attach; a 
previous capacity of motions which the animal is thus taught 
to exercise: and the facility with which this exercise 
is acquired forms one object of our admiration. What 
parts are principally employed, or in what manner each 
contributes its office, is, as hath already been confessed, 
difficult to explain. Perhaps the obscure motion of the 
bones of the feet may have their share in this effect. 
They are put in action by every slip or vacillation of the 
body, and seem to assist in restoring its balance. Certain 
it is, that this circumstance in the structure of the foot, 
viz. its being composed of many small bones, applied to, 
and articulating with one another, by diversely shaped sur¬ 
faces, instead of being made of one piece, like the last of 
a shoe, is very remarkable.* I suppose also, that it would 
be difficult to stand firmly upon stilts or wooden legs, though 
their base exactly imitated the figure and dimensions 
of the sole of the foot. The alternation of the joints, 
the knee-joint bending backward, the hip-joint forward; 
the flexibility, in every direction, of the spine, especially 
in the loins and neck, appear to be of great moment in 
preserving the equilibrium ofthe body. With respect to this 
last circumstance, it is observable, that the vertebrae are so 
confined by ligaments, as to allow no more slipping upon 
* [See Plate XI.] There is no part of the human frame which is more 
wonderfully constructed than the foot. It has the requisite strength to 
support the weight of the body, and often an additional burden; flexibility, 
that it may be adapted to the inequalities of the surface on which we tread; 
and elasticity, to assist in walking, running, and springing from the ground. 
This advantage we possess from the number of joints, the arch of the 
foot being composed of twenty-six bones. These bones have a con¬ 
siderable play on each other; and as each articulating surface is cover¬ 
ed with cartilage, the essential property of which is elasticity, the 
jarring is thus prevented which would result from a contact of the 
bones. 
“ The first question which naturally arises, is. Why there should be 
so many bones ? The answer is—In order that there may be so many 
joints ; for the structure of a joint not only permits motion but bestows 
elasticity. ’ ’—Pax ton 
