Mathematics consists of propositions of the form: P implies Q, but you never ask whether P is true.
Russell’s quote above is extremely incisive. Modern mathematics is indeed made up of statements of the form statement P implies statement Q. That is, we have ‘If statement P is true, then statement Q is true also.’ Usually, however, this structure is hidden, mainly to make mathematics more comprehensible – it would be hard to read if we always wrote it that way.
The second part of Russell’s quote is also true ...