31

G32

construction or an algebraical formula or array of signs.
The denotation of icons is essentially indefinite. Most
deductions require besides signs which term icons indices, that is signs
which deno represent their objects by being notably (though it may be
virtue of being connected with them in
fact, although this fact be but the actual occurrence of a thought.
only in the imagination) attached to connected with them in fact
Such are the letters attached
to a geometrical diagram, and the subjacent numbers often attached
to letters in algebra to show to what objects they refer; as when
x₁, y₁, z₁, x₂, y₂, z₃ denote the three coordinates of two different
points. The denotation of an index is essentially singular, since actual facts are singulars. Many
deductions cannot be performed, even in the mind, without the use