e on the science of medicine, we may
observe that, from the time of Hippocrates till almost the present
day, medicine has not deserved the name of a science but, as he
called it, of a conjectural art. At present however, by the
application of the laws of life, and of the new chemistry, there is
beginning to appear in physiology and pathology, something like the
simplicity and certainty of truth. In proportion as the laws of
animal nature come to be ascertained, the study of them will excite
more general attention, and will ultimately prove the most popular,
as well as the most curious and interesting branch of philosophy.

This must be productive of beneficial consequences to society, since
these truths, once impressed upon the mind by conviction, will
operate as moral motives, by which the sum of disease and human
misery cannot fail to be greatly diminished.

LECTURE XI.
OF THE NATURE AND CAUSES OF DISEASES.

In the two last lectures I have attempted to investigate the laws of
life. I now proceed to the most important part of our course, and for
which all the preceding lectures were intended to prepare us; I mean
the application of the laws of life to explain the nature and causes
of diseases, and the methods of curing them, which must always be
imperfect, and conjectural, unless the nature of the diseases
themselves be well understood.

We have already seen that life is constantly supported by the action
of the external powers which surround us, and that if the action of
these powers be properly regulated, and at the same time no other
powers be suffered to act on the body, we shall enjoy perfect health,
but if, on the contrary, the exciting powers which support life, act
either too feebly or too powerfully, then the functions will not be
performed with precision and vigour, but irregularly; the mind and
body will become deranged, and death will often take place many years
before the natural period at which that event might be expected.

As health is the greatest blessing which man can enjoy, it is natural
to think, that in the early ages of society, when men began to lose
sight of the dictates of nature, and feel the torture of disease,
they would regard with gratitude those who had contributed towards
their relief, and that they would place their physicians among their
heroes and their gods. In the early ages, however, diseases would be
very few, for it would not be till civilisation had made considerable
pro