s seeking new ideas.
We have common signs, he said, appealing to the eye, namely, written
characters, and others appealing to the ear, namely, articulate sounds;
we have none appealing to touch. "For want of such a language,
communication is entirely broken between us and those who are born deaf,
dumb, and blind. They grow, but they remain in a state of imbecility.
Perhaps they would acquire ideas, if we made ourselves understood by
them from childhood in a fixed, determinate, constant, and uniform
manner; in short, if we traced on their hand the same characters that we
trace upon paper, and invariably attached the same significance to
them."[76] The patient benevolence and ingenuity of Dr. Howe of Boston
has realised in our own day the value of Diderot's suggestion.

One or two trifling points of literary interest may be noticed in the
Letter on the Blind. Diderot refers to "the ingenious expression of an
English geometer that _God geometrises_" (p. 294). He is unaware
apparently of the tradition which attributes the expression to Plato,
though it is not found in Plato's writings. Plutarch, I believe, is the
first person who mentions the saying, and discusses what Plato exactly
meant by it. In truth, it is one of that large class of dicta which look
more ingenious than they are true. There is a fine Latin passage by
Barrow on the mighty geometry of the universe, and the reader of the
_Religio Medici_ (p. 42) may remember that Sir Thomas Browne pronounces
God to be "like a skilful geometrician."

An odd coincidence of simile is worth mentioning. Diderot says "that
great services are like large pieces of money, that we have seldom any
occasion to use. Small attentions are a current coin that we always
carry in our hands." This is curiously like the saying in the _Tatler_
that "A man endowed with great perfections without good breeding is like
one who has his pockets full of gold, but wants change for his ordinary
occasions." Yet if Diderot had read the _Tatler_, he would certainly
have referred to the story in No. 55, how William Jones of Newington,
born blind, was brought to sight at the age of twenty--a story told in a
manner after Diderot's own heart.

II.

It is proper in this place to mention a short philosophic piece which
Diderot wrote in 1751, his _Letter on the Deaf and Dumb for the Use of
those who Hear and Talk_. This is not, like the Letter on the Blind,
the examination of a case of the Intellect depriv