The chief end of language in communication being to be understood, words serve not well for that end, neither in civil nor philosophical discourse, when any word does not excite in the hearer the same idea which it stands for in the mind of the speaker. Now, since sounds have no natural connexion with our ideas, but have all their signification from the arbitrary imposition of men, the doubtfulness and uncertainty of their signification, which is the imperfection we here are speaking of, has its cause more in the ideas they stand for than in any incapacity there is in one sound more than in another to signify any idea: for in that regard they are all equally perfect.
That then which makes doubtfulness and uncertainty in the signification of some more than other words, is the difference of ideas they stand for.
5. Natural Causes of their Imperfection, especially in those that stand for Mixed Modes, and for our ideas of Substances.
Words having naturally no signification, the idea which each stands for must be learned and retained, by those who would exchange thoughts, and hold intelligible discourse with others, in any language. But this is the hardest to be done where,
First, The ideas they stand for are very complex, and made up of a great number of ideas put together.
Secondly, Where the ideas they stand for have no certain connexion in nature; and so no settled standard anywhere in nature existing, to rectify and adjust them by.
Thirdly, When the signification of the word is referred to a standard, which standard is not easy to be known.
Fourthly, Where the signification of the word and the real essence of the thing are not exactly the same.
These are difficulties that attend the signification of several words that are intelligible. Those which are not intelligible at all, such as names standing for any simple ideas which another has not organs or faculties to attain; as the names of colours to a blind man, or sounds to a deaf man, need not here be mentioned.
In all these cases we shall find an imperfection in words; which I shall more at large explain, in their particular application to our several sorts of ideas: for if we examine them, we shall find that the NAMES OF _M_IXED _M_ODES ARE MOST LIABLE TO DOUBTFULNESS AND IMPERFECTION, FOR THE TWO FIRST OF THESE REASONS; and the NAMES OF _S_UBSTANCES CHIEFLY FOR THE TWO LATTER.