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 endeavoured to frame them in such a manner as to express the most general and the most characteristic quality of the substances; and this was attended with the additional advantage both of facilitating the memory of beginners, who sind it difficult to remember a new word which has no meaning, and of accustoming them early to admit no word without connecting with it same determinate idea.

To those bodies which are sormed by the union of several simple subsiances we gave new names, compounded in such a manner as the nature of the substances directed; but, as the number of double combinations is already very considerable, the only method by which we could avoid confusion, was to divide them into classes. In the natural order of ideas, the name of the class or genus is that which expresses a quality common to a great number of individuals: The name of the species, on the contrary, expresses a quality peculiar to certain individuals only.

There distinctions are not, as some may imagine, merely metaphysical, but are essablished by Nature. “A child," says the Abbé de Condillac,