Some Penguin Classics breathe with the towering wisdom of the world’s great literary figures. And then there’s Voltaire.

The voluminous writings of Francois-Marie Arouet have been a mother-quarry of pseudo-profundity for over two centuries, of course, so in that respect this slim new volume from Penguin – a new translation by Desmond Clarke of the Master‘s 1763 book Treatise on Toleration – is unsurprising. The American presidential election campaign of 2016 culminated in a resounding victory for the forces of intolerance, one of a string of such victories being celebrated all around the world in governments both openly repressive and allegedly progressive. The lamps are going out all over the Europe of the still-young 21^st Century, so it’s a praiseworthy if predictable move on the part of Penguin, to issue this handy new edition of a short, compacted work in which Voltaire famously makes a case for rational inquiry, balanced consideration, and the toleration in the title.

He had in mind specifically religious toleration. The little treatise was sparked by the notorious case of the Huguenot shopkeeper Jean Calas, who in March of 1762 was sentenced to death for the crime of murdering his own son in the family home. Calas was innocent – his son had committed suicide – but he was also Protestant, and France’s vindictively Catholic authorities tortured Calas to death with extravagant brutality. Voltaire jumped on the bandwagon of the case for posthumously exonerating Calas, and the Treatise on Toleration was the loudest canon-blast in Voltaire’s arsenal. In it, he rails against the intolerance of France’s Catholic Church.

The case is laid out, as much as possible, along lines of logic and common sense. As Clarke summarizes in his perceptive Introduction:

If members of a political community accept the reciprocity of moral obligations and consider a principle such as the following: ‘Do not do what you would not like someone to do to you’, the implications for toleration are obvious. Each religious group or church must grant freedom of thought to others. Otherwise, they would face their fellow citizens with the following demand that cannot be satisfied simultaneously and reciprocally: ‘Believe what I believe and what you cannot believe, or you will die.’

The Master summons the whole history of Christianity to make all of his points about the long and complicated relationship the Church had always had with persecution and toleration – which calls for great chunks of cod-history buttressed with a delightful sub-profusion of footnotes (which Clarke further buttresses with notes of his own). To give him credit, Voltaire can very often make this kind of stuff interesting:

We are told that Nero persecuted Christians. Tacitus tells us that they were accused of setting fire to Rome and that they were then abandoned to the anger of the people. Has that accusation anything to do with their beliefs? Certainly not. Would we say that the Chinese who were slaughtered by the Dutch a few years ago in the suburbs of Batavia were sacrificed for their religion? No matter how much we might wish to deceive ourselves, it is impossible to claim that intolerance was responsible for the disaster that befell a few unfortunate half-Jews and half-Christians during Nero’s reign.

“If a government is not to have a right to punish human errors, those errors must not be crimes,” Voltaire writes. “They are crimes only when they are detrimental to society, and they damage society as soon as they inspire fanaticism. Therefore, in order to deserve toleration, people must begin by avoiding fanaticism.” And against this instance of fanaticism, our author was successful: Jean Calas was posthumously exonerated, and some of the worst of the creatures who broke him were cashiered. It’s enough to make a strong optimist wonder what brave Treatise on Toleration from 2017 Penguin will be reprinting in 2207.