small-pox varieties than species. Because the species of plants in
botanical systems propagate others similar to themselves; which does not
uniformly occur in such vegetable productions as are termed varieties.

In some other genera of nosologists the species have no analogy to each
other, either in respect to their proximate cause, or to their proximate
effect, though they may he somewhat similar in less essential properties;
thus the thin and saline discharge from the nostrils on going into the cold
air of a frosty morning, which is owing to the deficient action of the
absorbent vessels of the nostrils, is one species; and the viscid mucus
discharged from the secerning vessels of the same membrane, when inflamed,
is another species of the same genus, Catarrhus. Which bear no analogy
either in respect to their immediate cause or to their immediate effect.

The uses of the method here offered to the public of classing diseases
according to their proximate causes are, first, more distinctly to
understand their nature by comparing their essential properties. Secondly,
to facilitate the knowledge of the methods of cure; since in natural
classification of diseases the species of each genus, and indeed the genera
of each order, a few perhaps excepted, require the same general medical
treatment. And lastly, to discover the nature and the name of any disease
previously unknown to the physician; which I am persuaded will be more
readily and more certainly done by this natural system, than by the
artificial classifications already published.

The common names of diseases are not well adapted to any kind of
classification, and least of all to this from their proximate causes. Some
of their names in common language are taken from the remote cause, as
worms, stone of the bladder; others from the remote effect, as diarrhoea,
salivation, hydrocephalus; others from some accidental symptom of the
disease, as tooth-ach, head-ach, heart-burn; in which the pain is only a
concomitant circumstance of the excess or deficiency of fibrous actions,
and not the cause of them. Others again are taken from the deformity
occasioned in consequence of the unnatural fibrous motions, which
constitute diseases, as tumours, eruptions, extenuations; all these
therefore improperly give names to diseases; and some difficulty is thus
occasioned to the reader in endeavouring to discover to what class such
disorders belong.

Another difficulty attending the