Full Idea
While Russell and Whitehead used five primitive logical symbols in their system, Wittgenstein suggested in his 'Tractatus' that this be reduced to one.
Gist of Idea
Wittgenstein reduced Russell's five primitive logical symbols to a mere one
Source
Paul O'Grady (Relativism [2002], Ch.2)
Book Reference
O'Grady,Paul: 'Relativism' [Acumen 2002], p.44
A Reaction
This certainly captures why Russell was so impressed by him. In retrospect what looked like progress presumably now looks like the beginning of the collapse of the enterprise.