Pierre-Simon Laplace

The universe is a machine, the laws of which are known to us, and which we can predict with certainty.

The probability of an event is the ratio of the number of cases favorable to it, to the number of all possible cases, when nothing leads us to believe that any one of these cases should occur more readily than any other.

The theory of probabilities is only common sense expressed in numbers.

The weight of evidence for an extraordinary claim must be proportioned to its strangeness.

The present state of the system of nature is evidently a consequence of what it was in the preceding moment, and if we conceive of an intelligence which at a given instant comprehends all the relations of the entities of this universe, it could state the respective positions, motions, and general effects of all these entities at any time in the past or future.

Probability theory is nothing but common sense reduced to calculation.

It is India that gave us the ingenious method of expressing all numbers by means of ten symbols, each symbol receiving a value of position as well as an absolute value; a profound and important idea which appears so simple to us now that we ignore its true merit.

The simplicity of nature is not to be measured by that of our conceptions. Infinitely varied in its effects, nature is simple only in its causes, and its economy consists in producing a great number of phenomena, often very complicated, by means of a small number of general laws.

The curve described by a simple molecule of air or vapor is regulated in a manner just as certain as the planetary orbits; the only difference between them is that which comes from our ignorance.

Thus, the sublime results of celestial mechanics are the necessary consequences of the law of universal gravitation and of the small number of immutable laws which regulate the movements of the heavenly bodies.

The analytical equations, unknown to the ancients, which Descartes was the first to introduce into the study of curves and surfaces, are not restricted to the properties of figures, and to those properties which are the object of rational mechanics; they extend to all general phenomena. There cannot be a language more universal and more simple, more free from errors and obscurities...

Chance has no reality in itself; it is only a term for expressing our ignorance of the causes of phenomena.

Man follows only phantoms when he deviates from the calculus of probabilities.

The greater the probability of an event, the more we must believe it has occurred.

The word 'chance' then expresses only our ignorance of the causes of the phenomena that we observe to occur and to succeed one another in no apparent order.

The most important questions of life are indeed, for the most part, only problems of probability.

Let us run over the chain of human knowledge, and we shall see that it is entirely composed of a succession of probabilities more or less great.

The regularity which astronomy shows us in the movements of the comets doubtless exists also in all phenomena.

The mind has its illusions as the sense of sight; and in the same manner that the sense of feeling corrects the latter, reflection and calculation correct the former.

The true system of the world has been recognized, developed and perfected...