since we cannot teach what we do
not know, nor can properly undertake to instruct others while we are
ourselves in want of instruction. The next requisite is, that he be
master of the language in which he delivers his sentiments: if he treats
of science and demonstration, that he has attained a style clear, pure,
nervous, and expressive; if his topicks be probable and persuasory, that
he be able to recommend them by the superaddition of elegance and
imagery, to display the colours of varied diction, and pour forth the
musick of modulated periods.

If it be again inquired, upon what principles any man shall conclude
that he wants those powers, it may be readily answered, that no end is
attained but by the proper means; he only can rationally presume that he
understands a subject, who has read and compared the writers that have
hitherto discussed it, familiarized their arguments to himself by long
meditation, consulted the foundations of different systems, and
separated truth from errour by a rigorous examination.

In like manner, he only has a right to suppose that he can express his
thoughts, whatever they are, with perspicuity or elegance, who has
carefully perused the best authors, accurately noted their diversities
of style, diligently selected the best modes of diction, and
familiarized them by long habits of attentive practice.

No man is a rhetorician or philosopher by chance. He who knows that he
undertakes to write on questions which he has never studied, may without
hesitation determine, that he is about to waste his own time and that of
his reader, and expose himself to the derision of those whom he aspires
to instruct: he that without forming his style by the study of the best
models hastens to obtrude his compositions on the publick, may be
certain, that whatever hope or flattery may suggest, he shall shock the
learned ear with barbarisms, and contribute, wherever his work shall be
received, to the depravation of taste and the corruption of language.

[1] See Knox. Essay 50.

No. 119. TUESDAY, DECEMBER 25, 1753.

_Latius regnes, avidum domando
Spiritum, quam si Libyam remotis
Gadibus jungas, et uterque Poenus
Serviat uni._ Hor. Lib. ii. Ode ii. 9.

By virtue's precepts to controul
The thirsty cravings of the soul,
Is over wider realms to reign
Unenvied monarch, than if Spain
You could to distant Lybia join,
And both the Carthages were thine.