The 17th and 18th centuries, the so-called Age of Reason in Europe, were characterized by a widespread interest in miraculous healing and occultism (magic, kabbalah, and alchemy), and for every Diderot, Goethe, Hume, or Locke there was a mysterious swindler like “Count” Cagliostro or an amateur mystic like the sentimental novelist Julie de Krüdener. Flimflam and ignorance are subjects of The Dark Side of the Enlightenment, a book due out in July by John V. Fleming, emeritus professor of literature at Princeton University. We asked Fleming to pose questions about what’s to be gained today by studying the Age of Reason. Here are four culled from a longer list.

1. The Enlightenment was the great age of serious letter writing. Some French scholars of Freemasonry are working on the nature of epistolary exchange in the Enlightenment and the role that networks of correspondence play in the rapid transmission of new or controversial ideas. From a prominent correspondent writing from his private house or his communal lodge, letters could go out in all directions like radio waves, circles within concentric circles. Then each node might become its own center. The image often used at the time was that of the spider’s web. The “system” could approach the multiplying leverage of today’s chain letters. One fascinating historical project now underway involves the detailed study of epistolary spider webs, taking as an example the correspondence received by the Swiss physiologist and naturalist Albrecht von Haller (1708–1777). This correspondence comprised 14,207 letters sent from 446 posting stations throughout Europe.

In what ways does modern electronic communication amplify this Enlightenment system, and in what ways does it undermine it? Can we look forward to editions of the Collected Emails and Selected Tweets of the eminent scholars of our age?

2. In Dialectic of Enlightenment, Max Horkheimer and Theodor W. Adorno held that the Enlightenment attempted nothing less than “the disenchantment of the world.” A materialist and empirical sensibility, expressed with scientific and experimental attitudes, called into question all existing mythological systems. The triumph of Reason was remorseless, leaving little still standing of the old poetic universe. The poets themselves were aware of the onslaught. In 1611 John Donne published his “First Anniversary,” which included these famous lines:

And new Philosophy calls all in doubt,

The Element of fire is quite put out;

The Sunne is lost, and th’earth, and no man’s wit

Can well direct him where to looke for it.

Wordsworth’s disquiet was hardly less acute nearly two centuries later when he wrote in “A Poet’s Epitaph”:

Physician art thou? One, all eyes,

Philosopher! a fingering slave,

One that would peep and botanise

Upon his mother’s grave?

We are told that this century will belong to the biologists as the last one belonged to the physicists. Burgeoning new fields—molecular biology, neuroscience—promise or threaten to further disenchant and demythologize the inner worlds of our emotional and mental experience. What will be the response of the poets?

3. Immanuel Kant prefaced the first edition of his Critique of Pure Reason (1781) with the following sentence: “Human reason, in one sphere of its cognition, is called upon to consider questions, which it cannot decline, as they are presented by its own nature, but which it cannot answer, as they transcend every faculty of the mind.” This observation may account for the widespread enthusiasm, in the elite cultural and intellectual centers of 18th-century Europe, for esotericism, occultism, “mystical” Freemasonry, and certain religious phenomena that, from a current perspective, may seem very strange indeed.

Is Kant’s premise correct? Have more than two centuries of dramatic historical change and a huge increment in knowledge and learning answered any of the questions that in Kant’s view “transcend every faculty of the mind?”

4. If for the medieval period the queen of the sciences was theology, the Enlightenment’s scientific queen was alchemy. Some historians of the Enlightenment, perhaps embarrassed by this reality, have chosen to underplay or ignore it. Nonetheless, for most of the 17th and 18th centuries the enthusiasm for alchemy among bankers and archbishops was hardly less intense than among Rosicrucians and mystical Freemasons. If Sir Isaac Newton’s interest in the “Great Art” (alchemy) was eclipsed by his pursuit of biblical numerology, it was nonetheless keen. Modern historians of chemistry have shown that the experimental procedures of the alchemists, though founded in error, greatly advanced the discoveries of chemists. Of course the difference between an alchemist and a chemist, though perhaps greater than that between a hawk and a handsaw, was in linguistic terms no greater than the ossified Arabic article al still retained in the former.

Could etymological modernization add yet more dignity to any of the following: alcove, alembic, alfalfa, algebra, algorithm, Al Capone?