Few had seen the Habsburg king in years. But, in the early 1600s, a stream of letters issued from Prague Castle, where the reclusive Rudolf II had sequestered himself from the city below. Rudolf had an insatiable appetite for art, and his frantic missives commanded a Europe-wide network of agents, ambassadors, and dealers who serviced his obsession, procuring treasures on his behalf. In the first years of the seventeenth century, the object of his desire — the subject of his many dispatches — was a painting sitting above an altar in Venice.

In 1506, the German artist Albrecht Dürer had produced The Feast of the Rosary, an image of the Virgin and Child surrounded by high-status devotees including a pope and a series of kings, for the altarpiece of the German Church in Venice. For a century, the city’s transient population of German merchants had prayed before it, hoping for prosperity at Venice’s many marketplaces. Now, Rudolf wanted it for himself. He pestered the German community ceaselessly, sending his fixers to meet the church’s clergy, and haggling desperately over the terms of acquisition via letter. The congregation were reluctant to part with it, but in 1606, they finally relented. In the half-light of the building’s mediaeval interior, the painting was painstakingly prised from its fittings. It was wrapped in carpets to cushion it against damage, before being shouldered by a group of men handpicked for their strength and stamina.

The Feast of the Rosary was on its way to one of history’s greatest hoarders.

Hoarders have a mania for collection; they adapt their living space and habits to accommodate their things, and they tend to live in a state of clutter and chaos. In Possessed, a cultural history of the condition, Rebecca L. Falkoff writes that, ‘hoarding is unique because its diagnosis requires the existence of a material entity external to the patient’s psychic reality.’ In other words, hoarding shows the lack of boundaries between the inner, abstract world of the mind, and the outer, physical world. It is identified not by trying to understand the workings of the sufferer’s mind — as is more usual in mental health — but by casting an eye over what they own. This requires a degree of aesthetic judgement. If the person has taste, if their possessions are beautiful, their collection is legitimate. If not, it’s a hoard.

Many of the possessions, such as The Feast of the Rosary, that Rudolf poured so much time and energy into acquiring were beautiful and immensely precious. Hoarding is often understood as a product of the modern world, where junk — which appears ugly, because it lacks value — is plentifully available. Yet, the ‘beautiful’ and the ‘ugly’ are uncertain categories. Everybody knows that beauty is in the eye of the beholder. Rudolf had ‘taste,’ meaning he had wealth, connections, and that many of his belongings were undeniably pretty. Yet, his obsession with objects showed many of the characteristics typical to a hoarder. Rudolf’s life reveals much about psychology, art, and the fine and uncertain line that divides passion from compulsion.

Rudolf was part of the Habsburg dynasty, which ruled over a loose union of lands consisting of present-day Austria, Germany, Hungary, Croatia, and the Czech Republic between 1483 to 1806. He was born in Vienna in 1552 to Maximilian II and Maria of Austria. Collecting was a Habsburg family habit. Ferdinand I, Rudolf’s grandfather, liked Roman coins; Rudolf’s father, Maximilian, had a taste for antique statues.

At the age of 11, Rudolf was separated from his many siblings and packed off to the Spanish court of his uncle, Philip II, where he lived a lonely life for eight years surrounded by tutors and instructors who prepared him to rule. Being sent away from home took its toll on him. When he returned from Madrid, now a young man, courtiers commented on how stiff and aloof Rudolf’s manner had become. In 1583, he established his royal court in Prague. The Habsburgs had traditionally favoured Vienna as their seat, but the Ottoman Empire had invaded Hungary in 1526, and the Habsburgs had been fighting a lengthy land war on their border since. Prague put Rudolf at safe distance from the Turkish army’s advance.

The three decades of Rudolf’s reign were not, in a conventional sense, a success. Tensions between Catholics and Protestants, squabbles over territory, and power struggles between the Crown and the nobility threatened the stability of his lands. Rudolf was in no condition to manage these matters of state. He suffered bouts of intense ‘melancholy’ and psychological instability which — like a love of collecting — ran in the Habsburg line. After a particularly bad crisis in 1600, during which Rudolf became convinced he was possessed by the devil, he spent the remainder of his life closeted away in his private apartments. A Tuscan diplomat visiting Prague wrote a dispatch back to Florence, reporting that ‘disturbed in his mind by some ailment of melancholy, he has … shut himself off in his palace as if behind the bars of a prison.’

Locked in his castle, Rudolf devoted his life to accumulating the greatest collection of art and objects in all of Renaissance Europe. He owned paintings by Leonardo da Vinci, Paolo Veronese, Pieter Brughel the Elder, Titian and Hieronymus Bosch, as well as sculptures by Adriaen de Vries. Crammed into chests, cabinets, and cupboards in his castle were trinkets made out of mother of pearl and coral, brass plates engraved with curious pictures, clocks, headpieces and helmets, rare shells, spindly mathematical instruments, and the skins of thoroughbred horses imported from India. Notable curios in his collection included a phial of the earth from which God created Adam; two nails from Noah’s ark, and several stuffed animals, including a crocodile, a chameleon, and a bird of paradise.

All of these objects had a hold on Rudolf. Hoarding turns the idea of ‘possession’ on its head: objects possess their owners, rather than the other way around. Rudolf was helpless under their spell. He paid nine times the original price for The Feast of the Rosary – a fantastic sum, roughly £135,000 in today’s money. The strongmen who were ordered to carry the painting from Venice to Prague had to haul it over the Alps by hand, working in a relay to transport it over high ground. Mud, landslides, and flurries of early snow made it a gruelling journey. Bartholomeus Spranger, a Flemish artist known for his erotic and sensuous paintings, accompanied The Feast of the Rosary on its expedition. He later wrote that ‘the Alps still terrorise my dreams.’ When the painting finally arrived in Prague, Rudolf sent everyone from the room. He wanted to relish it alone.

Each of Rudolf’s acquisitions needed somewhere to go. Like a modern-day hoarder who makes pathways through stacks of newspapers or gives over their surfaces to mounds of defunct gadgets, Rudolf modified his castle to make room for his growing number of belongings. He built halls for his pictures and sculptures, as well as smaller rooms for jewels, books, and animals. The Kunstkammer, his collection of curios that included the nails from Noah’s ark, occupied a two-storey corridor. In a private room next to his bedchamber, Rudolf kept his favourite objects near at hand to examine and enjoy at his leisure.

Rudolf stayed close to his hoard; he believed his favoured possessions shielded him from harm. It was said – although of course we cannot know for sure – that Rudolf used his objects for protective rituals. When Rudolf felt under threat from his enemies, he would collect his Holy Grail (a fourth-century agate bowl said to have been used to collect Christ’s blood as he died on the cross), and a six foot ‘unicorn’ horn, probably a narwhal tusk. With these precious treasures beside him, he would draw a circle around himself, forming an invisible barrier that put him out of reach of danger.

Rudolf’s hope was that his collection would act as an encyclopaedia of the world from which he had retreated. His Kunstkammer was organised into themes. Naturalia covered natural history, zoology, botany, and mineralogy; Scientifica, clocks, watches, and celestial globes; and Artificialia coins and prints. Hoarders don’t tend to have a sequence for their things. To them, every object is equally delightful. Yet, many modern-day hoarders would also claim to have a system, or, more commonly, be on the verge of coming up with one. It isn’t clear when a collection (an ordered series of things) transforms into a hoard (a messy accumulation of objects). Rudolf occupied this uncertain zone.

There certainly was clutter in Rudolf’s collections. To collect the world is to make a mess. Knowledge is not a secure possession. It is constantly evolving; scholarship doesn’t have an end point, it is never complete. For that reason, a good encyclopaedia should encompass, rather than exclude. It appears that Rudolf’s system did not contain his drive to acquire — in fact, quite the opposite. Rudolf’s aunt, the Archduchess Maria of Styria, summarised the Sisyphean nature of his project. In an exasperated tone she wrote that ‘anything the Emperor learns about, he believes he has to have.’  If your intention is to produce an encyclopaedia of the universe by using objects, when do you stop buying things?

While it might seem chaotic to an outside observer, mess can hold potential. In a sprawling gallery or on crowded shelves, this can suddenly be seen in relation to that. Rudolf permitted trusted scholars, scientists, and alchemists into his apartments to admire his collection. By studying his assortment of curiosities — unmatched in size, diversity, and variety anywhere else — several of Rudolf’s circle made discoveries that shaped the modern world. For example, the court astronomer Tycho Brahe used Rudolf’s set of mathematical instruments to track the orbit of Mars. His successor, Johannes Kepler, used these observations as the basis for his laws of planetary motion, proving that planets move in elliptical orbits around the Sun.

To hoard is a creative act. Like many arts, whether painting, ceramics, or sculpture, hoarding is the re-arrangement of matter. Rudolf’s tireless accumulation of art, objects, and curios — his total possession by possessions — did not close him off. Rather, other ways of thinking presented themselves from the sprawl. In the case of his beloved court astronomers, for example, Rudolf’s determination to bring as much of the outside inside as possible permanently changed perceptions of the cosmic order.

Rudolf was ousted from power by his younger brother in 1611, and died one year later. The religious, dynastic, and territorial issues that he left unaddressed during his reign led to the outbreak of the Thirty Years’ War in 1618. Europe descended into one of the most bloody and destructive conflicts in its history; Rudolf’s collection was scattered.

When a Swedish army invaded Prague in 1648, the soldiers took away with them 470 paintings, 69 bronze statues, 179 ivory objects, and 600 agate and crystal goblets — substantial war booty, but only a small part of Rudolf’s stockpile. Somehow, The Feast of the Rosary was spared plunder. It remained at the palace, shuttered in its chambers. Today, it can be seen in Prague’s National Gallery. Some small consolation for those strongmen who hauled it over the Alps some 400 years ago, perhaps.