OBS. 2.—­A mere mark to which no sound or power is ever given, cannot be a letter; though it may, like the marks used for punctuation, deserve a name and a place in grammar.  Commas, semicolons, and the like, represent silence, rather than sounds, and are therefore not letters.  Nor are the Arabic figures, which represent entire words, nor again any symbols standing for things, (as the astronomic marks for the sun, the moon, the planets,) to be confounded with letters; because the representative of any word or number, of any name or thing, differs widely in its power, from the sign of a simple elementary sound:  i. e., from any constituent part of a written word.  The first letter of a word or name does indeed sometimes stand for the whole, and is still a letter; but it is so, as being the first element of the word, and not as being the representative of the whole.

OBS. 3.—­In their definitions of vowels and consonants, many grammarians have resolved letters into sounds only; as, “A Vowel is an articulate sound,” &c.—­“A Consonant is an articulate sound,” &c.—­L.  Murray’s Gram., p. 7.  But this confounding of the visible signs with the things which they signify, is very far from being a true account of either.  Besides, letters combined are capable of a certain mysterious power which is independent of all sound, though speech, doubtless, is what they properly represent.  In practice, almost all the letters may occasionally happen to be silent; yet are they not, in these cases, necessarily useless.  The deaf and dumb also, to whom none of the letters express or represent sounds, may be taught to read and write understandingly.  They even learn in some way to distinguish the accented from the unaccented syllables, and to have some notion of quantity, or of something else equivalent to it; for some of them, it is said, can compose verses according to the rules of prosody.  Hence it would appear, that the powers of the letters are not, of necessity, identified with their sounds; the things being in some respect distinguishable, though the terms are commonly taken as synonymous.  The fact is, that a word, whether spoken or written, is of itself significant, whether its corresponding form be known or not.  Hence, in the one form, it may be perfectly intelligible to the illiterate, and in the other, to the educated deaf and dumb; while, to the learned who hear and speak, either form immediately suggests the other, with the meaning common to both.

OBS. 4.—­Our knowledge of letters rises no higher than to the forms used by the ancient Hebrews and Phoenicians.  Moses is supposed to have written in characters which were nearly the same as those called Samaritan, but his writings have come to us in an alphabet more beautiful and regular, called the Chaldee or Chaldaic, which is said to have been made by Ezra the scribe, when he wrote out a new copy of the law, after the rebuilding of the temple.