More from Bertrand Russell
- Marriage and Morals (1929)
- Why I Am Not a Christian (1927), “The Emotional Factor”
People/Bertrand Russell/Quote

Thus mathematics may be defined as the subject in which we never know what we are talking about, nor whether what we are saying is true.
Mysticism and Logic and Other Essays (1918), Ch. 5: Mathematics and the Metaphysicians
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