Consultant, expert witness, and teacher.
The mathematics are not there for the joy of the analyst but because they are essential to the solution.
Karl Pearson, Notes on the History of Correlation (1920).
Whenever there is a simple error that most laymen fall for, there is always a slightly more sophisticated version of the same problem that experts fall for.
It is largely because of lack of knowledge of what statistics is that the person untrained in it trusts himself with a tool quite as dangerous as any he may pick out from the whole armamentarium of scientific methodology.
--Edwin B. Wilson (1927), quoted in Stephen M. Stigler, The Seven Pillars of Statistical Wisdom.
[Concerning scientific knowledge] Admission to its sanctuary, and to the privileges and feelings of a votary, is only to be gained by one means—sound and sufficient knowledge of mathematics, the great instrument of all exact inquiry, without which no man can ever make such advances in this or any other of the higher departments of science as can entitle him to form an independent opinion on any subject of discussion within their range.
-- Sir John Herschel, quoted by Augustus de Morgan (1872) in A Budget of Paradoxes. Emphasis in the original.