"Is heat the result of a vibratory motion of molecules? If... so, quantity of heat is simply quantity of motive power. As long as motive power is employed to produce vibratory movements, the quantity of heat must be unchangeable... but when it passes into movements of sensible extent, the quantity of heat can no longer remain constant."

"Liquuefaction of bodies, solidification of liquids, crystallization—are they not forms of combinations of integrant molecules?"

"Heat is simply motive power, or rather motion which has changed form. It is a movement among the particles of bodies. Wherever there is destruction of motive power there is, at the same time, production of heat in quantity exactly proportional to the quantity of motive power destroyed. Reciprocally, wherever there is destruction of heat, there is production of motive power."

"[[Energy|[M]otive power]] is, in quantity, invariable in nature; that it is, correctly speaking, never either produced or destroyed. It is true that it changes form, that is, it produces sometimes one sort of motion, sometimes another, but it is never annihilated."

"To take away to-day from England her steam-engines would be to take away at the same time her coal and iron. It would be to dry up all her sources of wealth, to ruin all on which her prosperity depends, in short, to annihilate that colossal power."

"What happens... in a steam-engine... ? The caloric developed in the furnace by the effect of the combustion traverses the walls of the boiler, produces steam, and in some way incorporates itself with it. The latter carrying it away, takes it first into the cylinder, where it performs some function, and from thence into the condenser, where it is liquefied by contact with the cold water... [T]he cold water of the condenser takes possession of the caloric... It is heated by the intervention of the steam as if it had been placed directly over the furnace. The steam is here only a means of transporting the caloric."

"Iron and heat are... the supporters, the bases, of the mechanic arts."

"Nature, in providing us with combustibles on all sides, has given us the power to produce, at all times and in all places, heat and the impelling power which is the result of it. To develop this power, to appropriate it to our uses, is the object of heat-engines."

"Steam navigation... tends to unite the nations of the earth as inhahitants of one country. ...is not this the same as greatly to shorten distances?"

"There is almost as great a distance between the first apparatus in which the expansive force of steam was displayed and the existing machine, as between the first raft that man ever made and the modern vessel."

"Notwithstanding the work of all kinds done by steam-engines... their theory is very little understood, and the attempts to improve them are still directed almost by chance."

"The phenomenon of the production of motion by heat has not been considered from a sufficiently general point of view. We have considered it only in machines... [for which] the phenomenon is... incomplete. It becomes difficult to recognize its principles and study its laws. ...[T]he principle of the production of motion by heat... must be considered independently of any mechanism or... particular agent. It is necessary to establish principles applicable not only to steam-engines but to all imaginable heat-engines, whatever the working substance and whatever the method by which it is operated."

"If human reason is incapable of discovering the mysteries of Divinity, why has not Divinity made human reason more clear-sighted?"

"A religion suited to the soul and preached by men worthy of respect would exercise the most salutary influence upon society and customs."

"Recherché pleasures cause simple pleasures to lose all their attractions."

"Let us not be exacting; perfection is so rare. Indulgence! Indulgence!"

"It may sometimes be necessary to yield the right, but how is one to recover it when wanted?"

"How much modesty adds to merit! A man of talent who conceals his knowledge is like a branch bending under a weight of fruit."

"Make intimate acquaintances only with much circumspection; perfect confidence in those who have been thoroughly tested. Nothing to do with others."

"Self-possession without self-sufficiency. Courage without effrontery."

"The strain of suffering causes the mind to decay."

"I rejoice for all the misfortunes which might have happened to me, and which I have escaped."

"Question thyself to learn what will please others."

"No useless discourse. All conversation which does not serve to enlighten ourselves or others, to interest the heart or amuse the mind, is hurtful."

"It must be that all honest people are in the galleys; only knaves are to be met with elsewhere."

"Hope being the greatest of all blessings, it is necessary, in order to be happy, to sacrifice the present to the future."

"The more nearly an object approaches perfection, the more we notice its slightest defects."

"To neglect the opportunity of an innocent pleasure is a loss to ourselves."

"When discussion degenerates into dispute, be silent; this is not to declare yourself beaten."

"[T]he production of heat alone is not sufficient to give birth to the impelling power: it is necessary that there should also be cold; without it, the heat would be useless."

"We say that man is an egotist, and nevertheless his sweetest pleasures come to him through others. He only tastes them on condition of sharing them."

"The truly wise man is he who loves virtue for its own sake."

"The production of motive power is then due... not to an actual consumption of caloric, but to its transportation from a warm body to a cold body... to its re-establishment of equilibrium..."

"War has been represented as necessary to prevent the too rapid increase of the population, but war mows down the flower of the young men, while it spares the men disgraced by nature. Hence it tends to the degeneration of the species."

"According to the system of modern economists, it would be desirable that the government should interfere as little as possible in the commerce and industry of the country. Nevertheless we cannot deny that in certain circumstances this intervention is very useful."

"Taxes are regarded by economists as an evil, but as a necessary evil, since they provide for public expenses. Consequently, economists think that if the government possessed sufficient revenues, in domains for example, the suppression of all taxes would be a desirable measure."

"Speak to every one of that which he knows best. This will put him at his ease, and be profitable to you."

"Never direct an argument against any one. If you know some particulars against your adversary, you have a right to make him aware of it to keep him under control, but proceed with discretion, and do not wound him before others."

"Speak little of what you know, and not at all of what you do not know."

"[I]f we should find about us only bodies as hot as our furnaces, how can we condense steam? What should we do with it if once produced?"

"Abstain from all pleasantry which could wound."

"Show neither passion nor weariness in discussion."

"Listen attentively to your interlocutor, and so prepare him to listen in the same way to your reply, and predispose him in favor of your arguments."

"Employ only expressions of the most perfect propriety."

"Why try to be witty? I would rather be thought stupid and modest than witty and pretentious."

"Egotism is the most common and most hated of all vices. Properly speaking, it is the only one which should be hated."

"[W]e have just described the re-establishment of equilibrium in the caloric, its passage from a... heated body to a cooler one."

"I do not know why these two expressions, good sense and common sense, are confounded. There is nothing less common than good sense."

"Men desire nothing so much as to make themselves envied."

"Love is almost the only passion that the good man may avow. It is the only one which accords with delicacy."