“It is a considerable point in all good legislation to determine exactly the credibility of witnesses and the proofs of a crime. Every reasonable man, everyone, that is, whose ideas have a certain interconnection and whose feelings accord with those of other men, may be a witness. The true measure of his credibility is nothing other than his interest in telling or not telling the truth; for this reason it is frivolous to insist that women are too weak [to be good witnesses], childish to insist that civil death in a condemned man has the same effects as a real death, and meaningless to insist on the infamy of the infamous, when they have no interest in lying.”

“It is a considerable point in all good legislation to determine exactly the credibility of witnesses and the proofs of a crime. Every reasonable man, everyone, that is, whose ideas have a certain interconnection and whose feelings accord with those of other men, may be a witness. The true measure of his credibility is nothing other than his interest in telling or not telling the truth; for this reason it is frivolous to insist that women are too weak [to be good witnesses], childish to insist that civil death in a condemned man has the same effects as a real death, and meaningless to insist on the infamy of the infamous, when they have no interest in lying.”

“When a fixed code of laws, which must be observed to the letter, leaves no further care to the judge than to examine the acts of citizens and to decide whether or not they conform to the law as written; then the standard of the just or the unjust, which is to be the norm of conduct for the ignorant as well as for the philosophic citizen, is not a matter of controversy but of fact; then only are citizens not subject to the petty tyrannies of the many which are the more cruel as the distance between the oppressed and the oppressor is less, and which are far more fatal than those of a single man, for the despotism of many can only be corrected by the despotism of one; the cruelty of a single despot is proportioned, not to his might, but to the obstacles he encounters.”

“I myself owe everything to French books. They developed in my soul the sentiments of humanity which had been stifled by eight years of fanatical and servile education.”

“Philosophers see no harm in the Jesuits other than in their effect on humanity and the sciences. The vulgar and especially the prejudiced only hate them from an envy and jealousy born out of conspiracy and intrigue at an organisation which overshadows them.”

“Our knowledge and all of our ideas are mutually connected; the more complicated they are, the more numerous must be the roads that lead to them and depart from them.”

“No man can be judged a criminal until he is found guilty; nor can society take from him the public protection until it has been proved that he has violated the conditions on which it was granted. What right, then, but that of power, can authorize the punishment of a citizen so long as there remains any doubt of his guilt?”

“In every human society, there is an effort continually tending to confer on one part the height of power and happiness, and to reduce the other to the extreme of weakness and misery. The intent of good laws is to oppose this effort and to diffuse their influence universally and equally.”

“The moral and political principles that govern men are derived from three sources: revelation, natural law, and the artificial conventions of society. With regard to its main purpose, there is no comparison between the first and the others; but all three are alike in that they all lead towards happiness in this mortal life.”

“If someone were to say that life at hard labor is as painful as death and therefore equally cruel, I should reply that, taking all the unhappy moments of perpetual slavery together, it is perhaps even more painful, but these moments are spread out over a lifetime, and capital punishment exercises all its power in an instant.”

“By 'justice', I understand nothing more than that bond which is necessary to keep the interest of individuals united, without which men would return to their original state of barbarity. All punishments which exceed the necessity of preserving this bond are, in their nature, unjust.”