If an author be supposed to involve his thoughts in voluntary obscurity, and to obstruct, by unnecessary difficulties, a mind eager in pursuit of truth; if he writes not to make others learned, but to boast the learning which he possesses himself, and wishes to be admired rather than understood, he counteracts the first end of writing, and justly suffers the utmost severity of censure, or the more afflictive severity of neglect.
Every author does not write for every reader; many questions are such as the illiterate part of mankind can have neither interest nor pleasure in discussing, and which therefore it would be an useless endeavour to level with common minds, by tiresome circumlocutions or laborious explanations; and many subjects of general use may be treated in a different manner, as the book is intended for the learned or the ignorant. Diffusion and explication are necessary to the instruction of those who, being neither able nor accustomed to think for themselves, can learn only what is expressly taught; but they who can form parallels, discover consequences, and multiply conclusions, are best pleased with involution of argument and compression of thought; they desire only to receive the seeds of knowledge which they may branch out by their own power, to have the way to truth pointed out which they can then follow without a guide.
The Guardian directs one of his pupils to think with the wise, but speak with the vulgar. This is a precept specious enough, but not always practicable. Difference of thoughts will produce difference of language. He that thinks with more extent than another will want words of larger meaning; he that thinks with more subtlety will seek for terms of more nice discrimination: and where is the wonder, since words are but the images of things, that he who never knew the original should not know the copies?
Yet vanity inclines us to find faults anywhere rather than in ourselves. He that reads and grows no wiser, seldom suspects his own deficiency: but complains of hard words and obscure sentences, and asks why books are written which cannot be understood.
Among the hard words which are no longer to be used, it has long been the custom to number terms of art. Every man, says Swift, is more able to explain the subject of an art than its professors: a farmer will tell you, in two words, that he has broken his leg; but a surgeon, after a long discourse, shall leave you as ignorant as you were before. This could only have been said by such an exact observer of life, in gratification of malignity, or in ostentation of acuteness. Every hour produces instances of the necessity of terms of art. Mankind could never conspire in uniform affectation: it is not but by necessity that every science and every trade has its peculiar language. They that content themselves with general ideas may rest in general terms; but those whose studies or employments force them upon closer inspection, must have names for particular parts, and words by which they may express various modes of combination, such as none but themselves have occasion to consider.
Artists are indeed sometimes ready to suppose that none can be strangers to words to which themselves are familiar, talk to an incidental inquirer as they talk to one another, and make their knowledge ridiculous by injudicious obtrusion. An art cannot be taught but by its proper terms, but it is not always necessary to teach the art.
That the vulgar express their thoughts clearly is far from true; and what perspicuity can be found among them proceeds not from the easiness of their language, but the shallowness of their thoughts. He that sees a building as a common spectator, contents himself with relating that it is great or little, mean or splendid, lofty or low; all these words are intelligible and common, but they convey no distinct or limited ideas; if he attempts, without the terms of architecture, to delineate the parts, or enumerate the ornaments, his narration at once becomes unintelligible. The terms, indeed, generally displease, because they are understood by few, but they are little understood only because few that look upon an edifice, examine its parts, or analyse its columns into their members.
The state of every other art is the same; as it is cursorily surveyed or accurately examined, different forms of expression become proper. In morality it is one thing to discuss the niceties of the casuist, and another to direct the practice of common life. In agriculture, he that instructs the farmer to plough and sow, may convey his notions without the words which he would find necessary in explaining to philosophers the process of vegetation; and if he, who has nothing to do but to be honest by the shortest way, will perplex his mind with subtle speculations; or if he, whose task is to reap and thresh, will not be contented without examining the evolution of the seed and circulation of the sap, the writers whom either shall consult are very little to be blamed, though it should sometimes happen that they are read in vain.