Euler calculated without effort, just as men breathe, as eagles sustain themselves in the air.
Quoted in D MacHale, Comic Sections (Dublin 1993)
The calculus of probabilities, when confined within just limits, ought to interest, in an equal degree, the mathematician, the experimentalist, and the statesman. Form the time when Pascal and Fermat established its first principles, it has rendered, and continues to render, services of the most eminent kind. It is the calculus of probabilities, which, after having suggested the best arrangements of the tables of populations and mortality, teaches us to deduce from those numbers, in useful character; it is the calculus of probabilities which alone can regulate justly the premiums to be paid for assurances; the reserve funds for the disbursements of pensions, annuities, discounts, etc. It is under its influence that lotteries and other shameful snares cunningly laid for avarice and ignorance have definitely disappeared.
Eulogy on Laplace