Magus: The Art of Magic from Faustus to Agrippa, Anthony Grafton, Allen Lane, £30

Sometime in 1506, the Benedictine abbot Johannes Trithemius, stopped at a tavern in the German town of Gelnhausen. There he encountered Doctor Faustus – then going by the name of Georg Sabellicus – handing out what were in essence business cards. Faustus was, the cards said, ‘chief of necromancers, an astrologer, the second magus, a reader of palms, a diviner by earth and fire’.

As Anthony Grafton notes in Magus, his rewarding new study of Renaissance magic, many really did see the diabolical in such claims; Luther, for one, described Faustus as ‘brother in law’ to the devil, though where some caught a whiff of sulphur, others smelled snake oil. Another contemporary, the Greek scholar Joachim Camerarius, dismissed Faustus as a purveyor of ‘juggler’s tricks’. Trithemius took another line: ‘You will find him not be a philosopher but a fool,’ he wrote of Faustus to a friend.

Yet at the very moment that Trithemius was condemning Faustus, he was battling almost identical accusations about himself and his work. A sometime house-guest, the French philosopher Charles Bovelles, had denounced Trithemius’s manuscript work on cryptography, the Steganographia, for its invocation of ‘barbarous and unheard-of… spirits (not to say demons)’. The book should be suppressed and never printed, he wrote.

Trithemius was indeed an expert on demonology. When the Holy Roman Emperor, Maximilian I, wanted to know everything there was to know about demons and witches, it was Trithemius he turned to. Maximilian was no neophyte in these matters; he had a magical ring named der Teufel – ‘the devil’ – which he attempted to use, unsuccessfully we assume, to repair his finances. What both Trithemius and Maximilian shared was a belief that there was such a thing as natural magic, which was distinct from the work of necromancers. The latter relied on malignant spirits for their effects, and those effects were illusory. ‘All the miracles of demons are phantasms,’ Trithemius wrote. Natural magic, however, occurred when ‘the secret application of a natural power by experts produced marvellous effects’. This was a longstanding tenet of magical thought. Pico della Mirandola, the late 15th-century Florentine scholar of the occult, cited the third-century Greek philosopher Plotinus in arguing that ‘the magus is Nature’s minister, not her Artificer’.

The nexus of religion and magic that Trithemius embodied was not a coincidence. The material world of late-medieval Catholicism was already also a spiritual and supernatural one: across Europe both religious houses and, increasingly, secular princes amassed large collections of holy relics – Grafton likens these collections to ‘celestial power stations’ – each of which was charged with divine power and could generate miracles. The Florentine hermeticist Marsilio Ficino wrote to the pope in 1478 to inform him that some relics of St Peter, recently discovered nearby, had caused ‘twelve great miracles in one month’.

This idea of occult – that is, hidden – power and divinity is at the heart of Renaissance magic. The question was, how to unlock it. Many practitioners – among them Pico and Ficino – stressed an ascetic, quasi-monastic self-cultivation as a necessary precursor of magical study. For Trithemius, it was a meditative form of Christian contemplation. ‘The mind and spirit of man can naturally do miracles,’ he wrote to Maximilian, ‘so long as it knows how to recall itself away from distraction and… above the senses, into unity.’

But it is wrong to conceive of the occult as an ethereal or otherworldly pursuit. Maximilian was not alone among Europe’s princes in being interested in the power that magic promised: Ficino translated the Hermetic Corpus, then thought to be written by an Egyptian magus in antiquity, at the request of Cosimo de’ Medici. Roger Bacon, a 13th-century Franciscan philosopher and authority on magic, believed that the rapid expansion of the Mongol empire, which threatened to engulf the Christian West, was due in part to their mastery of astrological talismans. Magic was terrifyingly real, the need to master it existentially urgent.

Magus is a serious and wide-ranging history of occult thought from the late-medieval period to the early 16th century. Renaissance magic has been the subject of academic study since the pioneering work of Frances Yates in the 1960s. What Grafton brings is both a sense of its roots in the textual scholarship of the late-medieval period – and in the methods of humanist study more generally – as well as of its relationship with contemporary developments in the mechanical arts, as practised by the likes of Brunelleschi and Leonardo.

The latter were exemplars of what Roger Bacon called ‘the science of experience’, by which he meant the practical ability to manipulate and transform the material world. ‘God has given men so much force of intellect’, the engineer Giovanni Fontana wrote, ‘that they have… brought about many things that nature herself could not have done.’ He cited hydraulic screws, block-and-tackle pulley systems, and siege artillery as examples.

While scholarly philosophers of magic admired the mechanical arts, the admiration was only half-returned. ‘The ones that girls turn down, those are the ones they instruct to study letters,’ wrote the Italian engineer, architect and cryptographer Leon Battista Alberti. Nevertheless, there is no avoiding the centrality of the written word, of manuscripts, books and the study of language, to occult studies. ‘Renaissance magicians were often bookish,’ Grafton writes with masterful understatement. After being shown Trithemius’s library of rare books, one humanist wrote, ‘I dreamt of nothing but books, and walking too could think of nothing but them.’

At a deeper level, God had made the world through words – the logoi spermatikoi – yet much of its meaning and power was obscured. Pico introduced a great deal of Kabbalistic thought into the study of the occult, and in particular a sense of Hebrew, the very language God used, as holding hidden power. As Cornelius Agrippa later wrote, God ‘knew all things before he named them, and… fashioned the names in such a way as to express [their] nature, quality and usage.’ The task of the magus then was to decipher the divine cryptography of creation.

In fact, it is the magi’s pioneering work on cryptography that enmeshes their world most deeply in our lives: thanks to the internet, encryption is ubiquitous. Some of their inventions, meanwhile, eerily foreshadow today’s apps and AI tools. Trithemius created a device that enabled someone unlearned in Latin to craft flawless sentences in the language; Alberti designed a tool which replicated the techniques of rhetoric for the benefit of unskilled orators. The former was one of the activities for which Bovelles attacked Trithemius: ‘How could he possibly achieve this without the help of spirits?,’ he thundered. But the point is that, while the effects were magical to the uninitiated, and often designed to appear so, the processes by which they were achieved were not.

It is easy to ridicule Renaissance magi. Contemporaries did. Trithemius, the 16th-century mathematician Girolamo Cardano said, ‘pretended that he had practised necromancy, when he should rather have been accused of stupidity’. Yet the questions they sought to answer – about human power over nature, about the relationship between language and reality, about the limits of materialism, about the great enigma of existence – are with us still. And with us still, too, is their search for meaning, for a sense of human worth and agency in a fast-changing, disruptive world.