Antoine Lavoisier

The chemical revolution is accomplished.

The art of reasoning is nothing more than a language well arranged.

We must not admit into our reasonings any proposition which is not founded on experiment and observation.

The balance is the instrument which has rendered the greatest services to chemistry.

The weight of the products of a chemical reaction is equal to the weight of the reactants.

The chemical elements are simple bodies which cannot be decomposed by any known means.

The air which we breathe is composed of two elastic fluids of different nature, one of which is respirable and the other not.

The art of concluding from experience and observation consists in evaluating probabilities, in estimating if they are high or numerous enough to constitute proof.

We must trust to nothing but facts: These are presented to us by Nature, and cannot deceive. We ought, in every instance, to submit our reasoning to the test of experiment, and never to search for truth but by the natural road of experiment and observation.

It is almost possible to predict one or two days in advance, within a rather broad range of probability, what the weather is going to be; it is even thought that it will not be impossible to publish daily forecasts, which would be very useful to society.

The whole art of making experiments in chemistry is founded on the principle: we must always suppose an exact equality or equation between the principles of the body examined and those of the products of its analysis.

I have tried... to arrive at the truth by linking up facts; to suppress as much as possible the use of reasoning, which is often an unreliable instrument which deceives us, in order to follow as much as possible the torch of observation and of experiment.

Languages are true analytical methods.

The impossibility of separating the nomenclature of a science from the science itself is owing to this, that every branch of physical science must consist of three things: the series of facts which are the objects of the science, the ideas which represent these facts, and the words by which these ideas are expressed.

Thus, while I thought myself employed only in forming a Nomenclature, and while I proposed to myself nothing more than to improve the chemical language, my work transformed itself by degrees, without my being able to prevent it, into a treatise upon the Elements of Chemistry.

Chance favours only the prepared mind.

For a long time I have been of the opinion that the principle of acidity was common to all acids, and I gave the name of oxygen to the principle or radical of the acidifying part, from οξυς acid, and γεινομαι I generate.

The human mind is so formed that it is much more struck by that which it does not know than by that which it does.

It is not enough to see, one must observe; it is not enough to hear, one must listen.

The quantity of matter before the operation is the same as after, the quality and quantity of the principles are the same, and nothing takes place beyond changes and modifications.