He held that 'the most helpful applications
of mathematics to economics are those which
are short and simple, which employ few symbols
and which aim at throwing a bright light on
some small part of the great economic move-
ment rather than as representing its endless
complexities'. ¹ Again: 'We owe several
valuable suggestions to the many investigations
in which skilled mathematicians, English and
continental, have applied their favourite method
to the treatment of economical problems. But
all that has been important in their reasonings
and results has, with scarcely an exception,
been capable of being described in ordinary
language: while the language of diagrams
or, as Professor Flemming Jenkin calls it, of
graphic representation could have expressed
them as tersely and as clearly as that of the
mathematics.' ² Yet again, in a letter to Bowley
written in 1906, Marshall wrote: 'I know I had
a growing feeling in the later years of my work
at the subject that a good mathematical theorem
dealing with economic hypotheses was very
unlikely to be good economics: and I went
more and more on the rules: (1) Use mathe-
matics as a shorthand language rather than as
an engine of enquiry. (2) Keep to them until

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