Full Idea
So long as I confine my thoughts to my own ideas divested of words, I do not see how I can easily be mistaken.
Gist of Idea
I can't really go wrong if I stick to wordless thought
Source
George Berkeley (The Principles of Human Knowledge [1710], Intro §22)
Book Reference
Berkeley,George: 'The Principles of Human Knowledge etc.', ed/tr. Warnock,G.J. [Fontana 1962], p.61
A Reaction
I think it was one of the great errors of twentieth century philosophy to say that Berkeley cannot do this, because thought needs language. Personally I think language lags along behind most our thinking, tidying up the mess. I believe in propositions.