“It is well not to spend one's symbols improvidently.”

Source: Isle of the Dead (1969), Chapter 1 (p. 29)

citation needed
Others

Source: Sayings of Sri Ramakrishna (1960), p. 308

[4] Symbol
Semiotics and the Philosophy of Language (1984)
Context: What is a symbol? Etymologically speaking, the word σύμβολον comes from σνμβάλλω, to throw-with, to make something coincide with something else: a symbol was originally an identification mark made up of two halves of a coin or of a medal. Two halves of the same thing, either one standing for the other, both becoming, however, fully effective only when they matched to make up, again, the original whole. … in the original concept of symbol, there is the suggestion of a final recomposition. Etymologies, however, do not necessarily tell the truth — or, at least, they tell the truth, in terms of historical, not of structural, semantics. What is frequently appreciated in many so-called symbols is exactly their vagueness, their openness, their fruitful ineffectiveness to express a 'final' meaning, so that with symbols and by symbols one indicates what is always beyond one's reach.

"On Going on a Journey"
Table Talk: Essays On Men And Manners http://www.blupete.com/Literature/Essays/TableHazIV.htm (1821-1822)

Vol. II: On Symbolical Algebra and its Applications to the Geometry of Position (1845) Ch. XV, p. 59
A Treatise on Algebra (1842)

Lawrence Summers in: David Warsh (April 27, 1986) "It Did Happen Here, Too", Boston Globe, p. A1.
1980s

However, by altering its m-configuration the machine can effectively remember some of the symbols which it has "seen" (scanned) previously.
On Computable Numbers, with an Application to the Entscheidungsproblem (1936)

Humor in Psychotherapy (2007)