OBS. 2.—­The first four points take their names from the parts of discourse, or of a sentence, which are distinguished by them.  The Period, or circuit, is a complete round of words, often consisting of several clauses or members, and always bringing out full sense at the close.  The Colon, or member, is the greatest division or limb of a period, and is the chief constructive part of a compound sentence.  The Semicolon, half member, or half limb, is the greatest division of a colon, and is properly a smaller constructive part of a compound sentence.  The Comma, or segment, is a small part of a clause cut off, and is properly the least constructive part of a compound sentence.  A simple sentence is sometimes a whole period, sometimes a chief member, sometimes a half member, sometimes a segment, and sometimes perhaps even less.  Hence it may require the period, the colon, the semicolon, the comma, or even no point, according to the manner in which it is used.  A sentence whose relatives and adjuncts are all taken in a restrictive sense, may be considerably complex, and yet require no division by points; as,

   “Thank him who puts me loath to this revenge
    On you who wrong me not for him who wrong’d.”—­Milton.

OBS. 3.—­The system of punctuation now used in English, is, in its main features, common to very many languages.  It is used in Latin, French, Spanish, Italian, Portuguese, Dutch, German, and perhaps most of the tongues in which books are now written or printed.  The Germans, however, make less frequent use of the comma than we; and the Spaniards usually mark a question or an exclamation doubly, inverting the point at the beginning of the sentence.  In Greek, the difference is greater:  the colon, expressed by the upper dot alone, is the only point between the comma and the period; the ecphoneme, or note of exclamation, is hardly recognized, though some printers of the classics have occasionally introduced it; and the eroteme, or note of interrogation, retains in that language its pristine form, which is that of our semicolon.  In Hebrew, a full stop is denoted by a heavy colon, or something like it; and this is the only pointing adopted, when the vowel points and the accents are not used.

OBS. 4.—­Though the points in use, and the principles on which they ought to be applied, are in general well fixed, and common to almost all sorts of books; yet, through the negligence of editors, the imperfections of copy, the carelessness of printers, or some other means, it happens, that different editions and different versions of the same work are often found pointed very variously.  This circumstance, provided the sense is still preserved, is commonly thought to be of little moment.  But all writers will do well to remember, that they owe it to their readers, to show them at once how they mean to be read; and since the punctuation of the early printers was unquestionably very defective, the republishers of ancient books should not be over scrupulous about an exact imitation of it; they may, with proper caution, correct obvious faults.