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(2) Translation of a text by my mother, Hilde de Haan, about architect Jan de Jong 

Towards the end of his life, Jan de Jong (1917-2001) was faced with a conundrum. Not interested in personal glory and perpetually shying away from the public eye, he still found that the achievement of his lifetime should be remembered. For over fifty years he had worked on a plot of land in Schaijk (Brabant, the Netherlands), where he had built amongst his residence and office an ensemble of larger and smaller buildings, gardens and courts. The location served as De Jong’s architectural testing ground. Drawing up his will, De Jong captured his wish to preserve this small collection of buildings, stating very clearly that this was not to glorify himself.

The ensemble should be remembered as his contribution to the Bossche School, a movement that had reached its peak in the 1960s. During this time, a small, fervent group of architects, predominantly from the southern part of The Netherlands, had formed around teacher and monk-architect dom Hans van der Laan 1904-1991. The group shared an investigation instigated by the monk-architect: to unravel the secrets of timeless architecture, or: of an architecture that transcends the whims of taste and the ravages of time.

Within this Bossche School, Jan de Jong had taken a special position. Around 1954 —when Dom Van der Laan himself had still barely built a thing and had merely taught others at the post-academic course on ecclesiastical architecture in ‘s-Hertogenbosch — he would already speak about ‘le nombre plastique’. This term referred to an ingenious measure-system developed by the monk-architect, based on a three dimensional version of the golden section. This three-dimensionality made the theory seem tailor-made for architectural use. Dom Van der Laan’s story was profound but on how to actually apply it, he was yet unsure. For this, he — quoting his own words – sought the support of practicing architects. He hoped to find these in the participants of the ecclesiastical architecture course. Not all students were equally amused by the monk’s request for guidance. But among those who were, De Jong’s interest shone out. De Jong became fascinated by the plastic number and even temporarily closed his own practice to investigate the possibilities of its use. ‘What I was able to do, I did no longer want, and what I wanted I did not yet master.’ De Jong’s investigation soon bore fruit: from 1956 he started working in a completely different way with the plastic number functioning as his guide. Pleased with this progress, dom Van der Laan soon acknowledged him as his most brilliant pupil.

In hindsight, the following happened. De Jong showed — himself and others around him, including dom Van Der Laan — how the plastic number could cause a revolution in architecture. He was the first architect at the course to opt for a sober, clear design language that really gave expression to the play of measures included in the theory of the plastic number. De Jong appeared to have a natural talent in doing so. Like a composer working with the western tone system, De Jong juggled with the plastic number. He chose, in other words, chords and melodies from the framework of this new measure-system to develop a new, bold architectural style.

Between 1956 and 1960 De Jong completed three groundbreaking churches. It was also in this period that he started to transform the land he owned in Schaijk into his architectural lab. The first experiment here resulted in a pavilion (1956), situated in the front yard. Placed in a corner of one of the walls surrounding the garden, four columns mark an outdoor space roofed by a corrugated sheet. Architecturally it couldn’t be more basic, yet every detail is considered: de asymmetrical entrance, the height of the parapet, the location of the columns and their size, all determined by the plastic number. From now on, De Jong would receive his clients in this pavilion, so they would experience the results of his new theory, and technique first hand.

In 1962 De Jong completed the first full-scale building on his premises according to his new vision: a workspace in the backyard, serving as a 1:1 scale model for the next stage of his research. Here he answered questions he had asked himself, like how to subdivide an interior space with columns and piers, and how to design a corner in an outdoor gallery with coloumns. Subsequently, the pace of de Jong’s development accelerated and soon his own home began to feel too tight. The English country-style dwelling, designed by De Jong in 1949 reflected how he had started his architectural career. Born as a farmer’s son in the small village of Lith (Brabant, The Netherlands), de Jong had as a young man accumulated certificates and diplomas in carpentry, masonry, surveying and architectural draftsmanship. As an experienced draftsman he had been proud of the 1949 building. He had married his wife, Riek de Groot, there and from the beginning it had housed both his practice and family life. But now, in 1962, it ceased to please him and his only hesitation against its demolition was the waste of capital. It was dom Van der Laan who encouraged and convinced him: ‘Jan, if you want this, you have to do this. We need built examples.’

The main building that resulted from this, completed in 1968, is more manifesto than home. The office and spacious residence enclose a walled courtyard with arbours on both sides and a centrally located pond. The living room spreads out over 24 meters. Inside, it is not the (sparse) furniture that sets the tone but the architectural composition: a concatenation of open spaces in which rows of columns indicate rhythm and size. Every detail, every piece of furniture, every spatial element is part of this; as if all pieces are themes in a composition of J.S. Bach. In De Jong’s architecture, practical demands were of secondary significance; the main incentive was, after all, to give an example of ‘lasting’ architecture: a ‘dwelling of the (ecclesiastical architecture) course’. The framing of the monumental entrance shows — per inscription in Latin — de Jong’s now ripened vision: “It befits a wise architect to arrange spaces so they serve as a roof for the body and a view for the mind”. (‘disponere molem condecet structorem + sapientem et ordinare spata + corpori tectum menti parare stratum’). This also fits the message dom Van der Laan conveyed from the 1960’s: buildings should not only serve their practical purpose but should be intelligible for our comprehension, and wholesome for the human mind.

As may be evident from the above, those who endeavour to understand De Jong’s oeuvre, should begin by understanding ‘le nombre plastique’. This also applied to us, Ids Haagsma and myself (Hilde de Haan), authors of both Gebouwen van het Plastische Getal (a lexicon and building guide, 2010) and a voluminous monograph on Jan de Jong (Jan de Jong: Pionier van het Plastische Getal, 2015). We had the privilege to be introduced to the philosophy of the plastic number by dom Hans van der Laan himself, when we met him in 1979 while conducting a series of interviews with architects for the weekly Dutch magazine Intermediair. Out of the 30 architects that took part in the series, the monk certainly left the deepest impression. The way he spoke about architecture was a world on its own. He posed a question: ‘Why do people actually make buildings?’ His answer: ‘Because the natural space is too vast for us, we need to create spaces that measure our size’

During the conversations we had, he would elaborate on this. To be able to experience the size of the architectural space, dom Van der Laan was convinced solid elements were of vital importance: columns and walls with perceivable width. These were supposed to be well ‘dimensioned’, that is to say: to the human scale, with the use of the plastic number. The plastic number was a necessary instrument to give the dynamic between spaces and solids a three-dimensional cohesion. He would explain why this measurement system was unique: it had a general validity because it was based on the way the human mind experiences reality. Dom Van der Laan was engaging. All the more so because he would show us his ‘morphotheque’ (in the English edition of De architectonische ruimte, ‘Architectonic Space’, this is called the form-bank): a box filled with wooden blocks that made the variable sizes in the system visible. In the blink of an eye he would build a magnificent, circling space. Overwhelming was the architectural structure of his own hand he would show us later: the now famous church with atrium and crypt of the Benedict abbey in Vaals. Architecture which, with its pure spaciousness, would come very close to what we thought to be eternal beauty. It was something we had rarely seen in contemporary architecture before.

Jan de Jong would, however, profoundly change this point of view. Applied within the oeuvre of De Jong, the measure-system appeared to be a much more abstract, exciting and complex instrument compared to what we had understood about it from dom Van der Laan. Knowing what we know now, this all makes sense. When we met dom Van der Laan in the late seventies, he must have thought the origin of the plastic number was not worth mentioning anymore. He did not speak a word, at least not in our presence, about the course he taught, which was discontinued in 1973 but where in the years prior to this, his theory had slowly ripened in interaction with the practicing architects. Ever since the publication of his book ‘De architectonische ruimte’ in 1977, dom Van der Laan had apparently aimed his ambition at one single objective: to disseminate his architectural theory he perceived to be finished by then. The book does not feature a single building, no architect is mentioned and architectural designs according to the theory are nowhere to be found. This was obviously a conscious decision but as a consequence the publication is rather detached from the practice of architecture. This became evident when we started studying the buildings of Jan de Jong.

The initiative for a publication about Jan de Jong arose in 2008 from de Jan de Jong Stichting (a foundation dedicated to preserve and document the work of Jan de Jong). The initial idea was a modest photobook about this ‘forgotten architect’; this would foster – in accordance with De Jong’s will - the preservation of his domain in Schaijk, his most pivotal building. The project got, to say the least, a little out of hand. To understand De Jong, we thought it necessary to understand his entire oeuvre. The architect’s archive appeared to be incomplete and this brought us to visit and interview many people who were somehow acquainted with the buildings of De Jong. What we eventually acquired was such an overwhelming amount of data, facts and historical documents (among which a nearly finished manuscript by De Jong: his own theory about urban planning and the plastic number) that we eventually decided to choose for a ‘two-stage rocket’: first a building guide (completed in 2012) to provide the overview, followed by a full monograph (completed in 2015). Our guiding theme became: what is the significance of the plastic number for architecture? With as a second question, derived from this: how did the practical application of the plastic number evolve? Research material for this last question seemed readily available: In De Jong’s archive we found a series of written lectures given by dom Van der Laan in the 1930’s and 1940’s about the predecessor of the plastic number: the ‘ground ratio’. We also stumbled across lectures the monk gave in the fifties and sixties at the ecclesiastical architecture course, when De Jong was a student and (later) a mentor there. This enabled us to accurately align the development of the theory with the succession of works completed by De Jong. Next to the theory we found other sources of inspiration: travel journals of trips De Jong had made abroad and shelves lined with books about architecture in remote and ancient cultures.

Our chief provider of information became Wim Ramselaar (1935-2013), engineer trained in Delft and lecturer at the TU Eindhoven. From 1961 tot 1968, during the golden years of the ecclesiastical architecture course, he worked as a collaborative architect at De Jong’s practice. De Jong’s passing in 2001 marked an occasion for Ramselaar to chronicle his memories of those days with the use of his own diaries. This unusually frank account of De Jong’s daily practice became an integral part of the monograph. Wim Ramselaar brought Jan de Jong’s way of working alive to us. He knew exactly what his work in the sixties had entailed. Moreover, he was willing to help us analyse De Jong’s designs. Quite often these proved a tricky puzzle to solve: detailed drawings were missing and explanations had rarely been saved. But often it was possible to measure the millimetres on the drawings, and so distil the way the plastic number had been used. Again and again we discovered De Jong’s typical measurement choices, his favourite themes, with increasing ingeniousness applied in many shapes and variations. On 26 December 2013, Wim Ramselaar passed away, two years before the completion of the monograph. Despite his premature departure, his input characterises the entire book.

During our research, we made an interesting discovery. In Jan de Jong’s experience, the plastic number was an instrument offering a multitude of possibilities in his work as an architect. Dom Van der Laan had seen it — mostly — as one of the steps in a more comprehensive architectural theory. This difference marks the lives of them both. Where dom Van der Laan designed only a handful of buildings and acquired fame with De architectonische ruimte, de Jong was an architect, born and bred, who would apply the measuring-system in hundreds of commissions, in ever changing and evolving ways. For both dom Van der Laan en De Jong, the plastic number was an instrument with which timeless architecture could be composed, but the way they applied the theory in their work was fundamentally different. Through our research into the oeuvre of Jan de Jong we deepened our understanding of the plastic number and experienced that real comprehension and insight is only pos-sible when the viewpoints of theory and practice are combined. 

A short clarification here is essential. Reader, brace yourself and take the time to digest the below mentioned explanation of le nombre plastique. The basis of which is a mathematical discovery made by Dom Van der Laan himself around 1928 (proof of this are the lectures by dom Van der Laan during WWII). During this time he was looking for a more refined ratio than the golden section and found this in 1 : x : x2 = x : x2 : (1+x). This can be simplified to x3 – x = 1. This can be calculated: 1,325 (circa 4:3) or 0,755 (circa 3:4). As a comparison: when using the golden section, the following applies: 1 : a = a : (1+a), which we note as a2 – a = 1, and calculate as 1,618 (5:3) or 0,618 (3:5). Van der Laan never mentioned this basic discovery in his later work. In De architectonische ruimte (1977) he only writes about ‘an extraordinary ratio, namely circa ¾’. But to really understand his measure-system, this mathematical discovery is indispensible. The core of the plastic number is a sequence of sizes that accrue 1,325 times their size per increment (circa 4/3 ) (or reduce in size with 0,755, circa ¾). The sequence is in principle infinite, but dom Van der Laan applied a few ingenious interferences that made it manageable for practical use. First of all: he decided to arrange the sequence in octaves, so that the smallest size of the octave would be the biggest size of the subsequent, smaller one. The decision for octaves is mathematically convenient: 1 x 1.3257 is a more or less round number, namely circa 7. And the arrangement was also practical: a series of seven is still intelligible to the human eye, with larger numbers this becomes difficult. By making this division into smaller series, dom Van der Laan made the seemingly infinite sequence manageable. Another interference was that Van der Laan decided to simplify the different sizes in the series into fractions: 1/7, 1/5, 1/4,1/3, 3/7, 4/7, 3/4, 1. This is clear and straightforward, but obviously not entirely correct. Take for example the 1/5 size, which has the largest deviation. In the sequence, every size is roughly 4/3 larger than its predecessor, but 1/7 x 4/3 = 4/21, not 4/20 (=1/5). The problem of deviation was solved by giving every size some latitude (initially called the ‘margin’) of approximately 1/49. This fits with the mathematical system (1/49 = 1/7 x 1/7) but it remained a choice, serving its purpose in ease of usage. 

In the early 1950’s, when Jan de Jong was introduced to le nombre plastique, its complexity was still legible in the way it was noted (by both dom Van der Laan as the students at the course). Representative for this is the ‘timetable’ Jan de Jong would use his entire life. This small table lists four or sometimes even five sequences neatly placed next to each other in both decimal numerical notation and fractions. The permitted ‘margin’ is mentioned per size. Also noted are the double sizes, which had been woven into the system in the 1940’s. Once you comprehend the way it works, the system is incredible, comparable to the tone system in Western music. When the main measures for a building have been determined, one can draw from the cohesive measure sequences for the design of the spatial layout, façade structure and further details. De Jong developed this approach continually so it became an intriguing game with margins, dissonances and themes that would reoccur in his designs at different points and on different scale levels. But note: the plastic number remained, also for Jan de Jong, merely an instrument, no destination. The purpose of his architectural practice remained: to create a timeless architecture. For this purpose dom Van der Laan developed the rest of his theory, drawing inspiration from the lessons of Vitruvius, while De Jong preferred to seek his teachers in the architecture of old villages and towns.

Jan de Jong became largely forgotten. Dom Van der Laan acquired world fame. The roots of this diversion started to show in the late 1960’s. Shortly before Jan de Jong’s building in Schaijk was completed in 1968, dom Van der Laan’s abbey church in Vaals was consecrated in 1967. Now that dom Van der Laan had completed his own masterpiece, and (around the same time) relocated from Oosterhout in Brabant to Vaals in Zuid-Limburg (a more southern province of The Netherlands), the distance — both physically and mentally — between him and his most brilliant pupil grew. This distance even furthered when the ecclesiastical architecture course was discontinued in 1973. This termination was not only due to the participants and teachers, but also to a new era in which the popularity of churches declined and (church) authorities were challenged. Furthermore, many of the alumni of the course now had established architecture practices, with busy agendas in which there was little room for refined measuring games. Jan de Jong remained an exception, staying true to his initial zeal. The fact he remained in Schaijk, where he had his architectural testing ground, helped. He did not want a large practice, rather the opposite. Around 1970 he even fired his entire staff apart from one draftsman (Mart van den Broek) and a part-time surveyor. In terms of his work this enabled him to flourish unprecedentedly, the fruits of which he hardly shared with his congenial colleagues. He designed large town halls, delved into city renewal plans and restorations and developed his theory about city planning and the plastic number. While dom Van der Laan, with his important book and church, thought to have reached an end point, Jan de Jong was making a fresh start. In essence he still endorsed dom Van der Laan’s theory while noticing the omissions, for instance where it regarded city planning or exterior design: in these fields he continued his search and research, and followed his own way. He stayed true to the subdivision of spaces with columns and thick walls, just as the musicality of the plastic number is recognisable in every one of his buildings. But the theory did not limit him at all, as his later work shows: he even designed in wood, using post-modern shapes and configurations.