UNITÉ DE DOCTRINE – CONTINGENCY OF PRACTICE? TOWARDS A RE-READING OF TWENTIETH CENTURY PRINCIPLES OF BUILDING HERITAGE CONSERVATION

The theoretical framework of building heritage conservation is not necessarily a predefined set of tenets and axioms with potentially universal significance, but a result of particular challenges and practices bound in time and place. In this article, the guidelines of building heritage conservation in Switzerland in the last century are outlined briefly with reference to the broader European theoretical discourse. Focusing on the contradictions between the theoretical position and practical work of Linus Birchler, it argues for the necessity to re-read and assess our principles of building heritage conservation in relation to the specific built cases they originated from.


Introduction
Within the war-torn, fractured historic landscape of twentieth century Europe, multilingual and multicultural Switzerland appears as an island of continuity and tedious consonance, at least in regard to the history of preservation of historical monuments. Without external disturbances, the practice of building heritage conservation 1 in Switzerland developed under a persisting "unité de doctrine". At least, such continuity of basic principles has been claimed repeatedly -and expressed prominently again by then President of the Swiss Confederation Pascal Couchepin in 2007 (Caviezel, 2017, p. 201). Evoking consistent professional accord in regard to the preservation of cultural heritage, in its original 1 Though this article deals with architectural restoration in the middle of last century, the term building heritage conservation is used to denote the field and its purpose in general, as an equivalent to the German term Baudenkmalpflege. The contemporary guidelines referred to do not necessarily distinguish between the care and preservation of architectural monuments and works of art, that is between building heritage conservation, conservation-restoration and the preservation of cultural heritage in general, Denkmalpflege.
understanding the phrase reaffirmed the continuous succession of teacher-student relationships from Johann Rudolf Rahn (1841Rahn ( -1912 to Josef Zemp (1869Zemp ( -1942 to Linus Birchler (1893-1967, the decisive president of the Swiss Federal Commission for Monument Preservation from 1942 to 1963, who can be attributed to have coined the phrase (Birchler, 1964, p. 115). Following Birchler as president of the aforementioned commission and as professor at ETH Zurich respectively, Alfred A. Schmid (1920Schmid ( -2004 and Albert Knoepfli (1909Knoepfli ( -2002 both secured the lasting influence and alleged continuity of the "doctrine" in the second half of last century. In its introduction, the current Guidelines for the preservation of built heritage in Switzerland (EKD, 2007) again refer to Rahn, Zemp and Birchler and a by now canonical list of three preceding guidelines associated with them, which will be introduced successively in the first part of this article. Effective for the remaining of the century, Birchler's guideline especially shows no immediate discrepancy to the principles of the Venice Charter of 1964. However, its actual meaning can only be assessed in regard to his practice of restoration, which will be outlined by three significant cases chosen by Birchler himself to exemplify his position.

The canon of the Swiss guidelines of building heritage conservation
Edited by the Swiss Society for the Preservation of Historic Monuments (Schweizerische Gesellschaft für die Erhaltung historischer Kunstdenkmäler) in 1893, the so-called Anleitung zur Erhaltung von Baudenkmälern und zu ihrer Wiederherstellung is the first publication of principles of building heritage conservation in Switzerland of significance (Fig. 1).
In 1886, the newly created Swiss Federal Commission responsible for the acquisition and conservation of historic monuments had been created out of the board of this private society. Five years later, with the establishment of the Swiss national museum (the Schweizer Landesmuseum in Zurich), the same board was in danger of losing this function and the accompanying official privileges (Wassmer, [1964], p. 5). Though the responsibility for acquisitions of works of art could not be retained, the board was able to remain officially in charge of recommending federal contributions to architectural restoration from 1892 onwards (Erhaltungsgesellschaft, 1892, p. 2). Obviously, the purpose of publishing guidelines a year later was more about publicly asserting the society's expertise and justifying its official position then about offering practical advice. Attributed to Rahn in the current Guidelines (EKD, 2007), the publication of the Anleitung was actually strongly influenced by architect Heinrich von Geymüller   (Knoepfli, 1972;Haupt, 2014, p. 62). However, these first Swiss guidelines on building heritage conservation were not directly based on the actual practice of those who issued them. Basically, the Anleitung was a slightly adapted German translation of two interrelated guidelines by the Royal Institute of British Architects, the 1888 reviewed edition of the General Advice to Promoters of the Restoration of Ancient Buildings and Hints to Workmen engaged on such Restorations and Repairs. 2 The original edition of both separate documents on Conservation of Ancient Monuments and Remains had been published in 1865. Initiated some years before by Sir Georg Gilbert Scott (1811Scott ( -1878, the RIBA guidelines basically summed up his own practical experiences. In turn, the document was a late answer of the professional architects to the pamphlets of the Cambridge Camden Society from the early 1840s, namely A few words to Church Builders (1841) and A few words to Churchwardens (1842) (Scott, 1862, p. 93). These pamphlets had been enormously influential in early neo-gothic church restoration movement in Britain (Brandwood, 2000, pp. 54-55) before being replaced gradually by Scott's more "faithful" approach (Scott, 1850). The RIBA's Advice even mirrored the double addressing, later to be copied in the Swiss translation without further motivation. As is well known, the RIBA's original Advice became the object of critical assessment by Scott's former apprentice John James Stevenson (1831Stevenson ( -1908 in 1877 (Stevenson, 1877), acting on behalf of the newly established Society for the Protection of Ancient Monuments (Tschudi Madsen, 1976). The reviewed edition of 1888 used by the Swiss preservationists had just altered the criticised points (Putz, 2015, pp. 181-183; A6-A21). Though the SPAB itself would publish its Notes on the Repair of Ancient Buildings not before 1903, thus, ironically, the first Swiss guidelines on building heritage conservation with an official significance were based on a document already considered outdated by the discipline's more progressive protagonists. Yet the Swiss discussion was far from detached from the evolving international field of building heritage conservation. In Das Restaurieren Josef Zemp made a noteworthy contribution to the fundamental German discussion at the turn of last century. In his article, published in three slightly different versions in 1907 and 1908 (Zemp, 1907a;1907b;1909) of the profession of architecture (Fig. 2). In his considerations, Zemp strongly followed the arguments and positions of Cornelius Gurlitt (1850Gurlitt ( -1938 in Vom Restauriren (1903), re-published in 1904 in the book Über Baukunst, a copy of which had been forwarded to Zemp by Gurlitt. According to the exchange of letters between the two, 3 Zemp especially found reassurance in the following line: "Grundregel aller Erneuerung sollte sein, dass sie keine Täuschung über das Alter erneuerter Teile herbeiführt, dass aber alles das, was neu gemacht werden muss, um das übrige Alte zu erhalten, auch als neu erscheine." 4 (Gurlitt, 1904, p. 18) This modernist principle of building heritage conservation reflects a different perspective to Georg Dehio's well-known "konservieren, nicht restaurieren". Though consistent in their repudiation of typical nineteenth century restoration, stylistic purification and historicistic reconstruction; the art historian Dehio considered conservation as a task for artistically and technically trained archaeologists (Dehio, 1905, p. 24), whereas the architect Gurlitt (and subsequently Zemp) upheld the cautious and scientifically hedged artist and architect. It is for this reason he opted for a domain of contemporary design (Gestaltung) within the care of historic monuments, especially in additions. 3 Letter from Josef Zemp to Cornelius Gurlitt, January 8 1904, (Brief 104/001, Nachlass Cornelius Gurlitt, Universitätsarchiv der TU Dresden). 4 "As a general rule, renovation work must not deceive the true age of renewed parts; instead, everything which has to be made anew to preserve the remainder should also appear as new. " (transl. by Author). It was not before a reprint in 1947 that Zemp's article became highly influential within the Swiss discussion. Zemp's concise parole "Das Alte erhalten, das Neue gestalten" / "Conserver l'ancien, adapter le nouveau" (Zemp, 1907a, p. 258) has been cited countlessly since. Yet the scope and responsibility of such Gestaltung of the historic artefact was now to be redefined by the art historian Linus Birchler. Birchler's contribution to the Swiss guidelines of building heritage conservation, a list of twelve principles to be applied by the Federal Commission first outlined in his Restaurierungspraxis und Kunsterbe in der Schweiz (1948), was the most influential and enduring, being valid officially for about half a century (Fig. 3). After the war, Birchler had visited Poland, France, Italy, and Germany; and knowing form first-hand experience about the enormous reconstruction efforts he did not want his country to stay behind. Published just at the beginning of the nation's post-war economic upswing, the little brochure's main aim was to secure more and enlarged funding for cultural heritage preservation in general. It was actually sent by Birchler to every member of the national assembly, and in the mid 1950´s he finally succeeded. Thanks to Birchler, the preservation of cultural heritage truly became considered a national obligation.
Again, the list of principles was based on a template. In 1930, Birchler's predecessor as president of the Federal Commission, Albert Naef (1862-1936) had outlined a sober list of measures of building conservation for which federal subsidies could be assigned. 5 Naef 's internal Rapport relative à l' allocation des subventions federale pour travaux des conservation clearly reflected the economic depression of the early 1930s in aiming to secure at least funding for basic conservation. In fourteen articles he restricted the care for ancient buildings to core principles of repair and substantial conservation work. 6 In regard to the restrictions of Naef 's Rapport, Birchler´s principles re-defined building heritage conservation in times of post-war prosperity. His principles successfully initiated the expansion of the preservation of building heritage, yet coherently, the scope of construction work considered appropriate expanded as well, as will be shown. Additionally, Birchler´s list of principles was far from fixed. Originally outlined in twelve points, in successive lectures he only mentioned eleven or ten, depending on audience. In 1957, at the "Congrès International des Architectes et Techniciens des Monuments Historiques" in Paris, the first post-war international conference on building heritage conservation and the predecessor of the "IIe Congrès International de la Restauration" in Venice 1964, Birchler in effect presented fourteen principles, of which only eleven were identical with the original (Birchler, 1957b). 5 Naef, though not mentioned in the guidelines of 2007, is not omitted from the history of preservation in Switzerland altogether, but he certainly was not referred to much often by Birchler. Famous for his work at Chillon and Romanmontier, Naef of course was a French speaking Swiss, a protestant, and an architect (unlike Rahn, Zemp and Birchler). Generally, the principles outlined by Birchler (Birchler, 1948, pp. 14-19;Birchler, 1957b, pp. 101-104) are in accordance with contemporary conservation theory. He negated the possibility of absolute standards in building heritage conservation, every case has to be regarded individually. He considered every historic period of art valuable; and as restorers must not engage in stylistic reconstruction, modern additions must not imitate historic forms. He asked for the personality of the involved architect to be restrained and no modern building materials to be used in historic fabrics. Quoting Josef Zemp ("Der Bau restauriert sich im Grunde selber. " / "Le bâtiment se restaure lui-même."), he seemingly recommended thorough building surveys and analysis before intervention (Birchler, 1948, p. 15;Birchler, 1957b, p. 101). And quoting Naef ("Tous les relevés sont faux."), he pointed not only to the inconsistencies of historic planning documents, but to the difference of two dimensional representation and three dimensional reality (Birchler, 1957b, p. 103). For the Swiss conservation experts attending the conference in Venice, the declaration of 1964 was no reason to question their general practice (Schmid, 1993). In their essential points, the Swiss guiding principles by Birchler of 1948 and1957 and the Charter of Venice showed no discrepancy. In several major parts, like the differentiation of reconstruction, anastylosis, renovation, restoration and conservation (Birchler, 1948, p. 7;Birchler, 1957b, p. 101), Birchler´s text even foreshadowed the Charter of Venice.

Three church restorations by Linus Birchler
To assess Birchler's principles in a historic perspective, one has to relate them to actual practice. Though the principles can still be considered in accordance with most of today's conservation ethics, his practice of restoration defies them. The cited examples are telling, as the extensive transformation of the monuments was not, as often criticised, intended by the responsible architect, but requested by the art historian and preservationist. The restoration of the catholic town church of Baden 1936/37 was one of the first projects Birchler became involved with as member of the Federal Commission. 7 In the early 1930s, the church still had its neo-gothic decorum. The architect's original project had only planned for a repair of plaster and restoration of derelict stone jambs of the entrance portal. However, the churchwardens applied for federal funds. According to the recommendations of the acting federal expert, Birchler, the complete façade of the historic monument was purified to its current state, enlarging building costs and making additional new parts like a porch necessary (Kuonen Ackermann, 2002;Putz, 2015, pp. 189-192). The destruction of the neo-gothic façade resulted in the need of a new design for the stone jambs of the main portal. Accidentally, older jambs were found during demolition, luckily similar to the ones already designed by Birchler. As Birchler confirmed in a later recollection, the project in Baden in particular informed his principles of building heritage conservation (Birchler, 1948, pp. 19-20;Birchler, 1960, p. 341). Twenty-three years later, obviously indifferent to his own inconsistencies, he defended his early work as aiming at the original appearance and creating historic authenticity. "Unser 7 Birchler was appointed member of the Federal Commission in 1930 and became engaged as an official federal expert on behalf of the Commission's president. In 1936, he became vice-president and from 1942 till 1963 he acted as its president.
Just around the Paris conference of 1957, Birchler became heavily involved in two other church restorations. Despite the original differences both churches became strikingly similar in their interior appearance. The Augustinerkirche in Zurich was the former church of one of the city's medieval monasteries which had been reworked in 1843 in a neo-gothic fashion by Ferdinand Stadler (1813-1870). Its restoration by architect Max Kopp (1891Kopp ( -1984 under the guidance of Linus Birchler from 1957 to 1959 followed earlier repair work in 1936/37 (Abegg & Wiener, 1999). As in Baden, the original plans of the architect were rather limited in scope, but after federal funds were requested for the restoration, Birchler became involved. In an statement just after his first short visit to the building, he asked for the demolition of the interior neo-gothic plaster vaults and the introduction of a simple flat wooden ceiling. 9 Without proper survey and planning, the new ceiling happened to cut into the large window at the church's entrance façade, which after thorough discussion became remodelled as well (Putz, 2015, pp. 214-226). 8 "Everywhere, we aimed at the most accurate reconstruction of the old entity, ..." (transl. by Author). 9 The request was stated in a letter to Heinrich Peter, who Birchler asked to act as his local expert for the project. Letter from L. Birchler to H. Peter, April 17, 1957, Schriftverkehr Augustinerkirche Zürich (EAD -EKD -1841, 756), EAD, Graphische Sammlung der Nationalbibliothek Bern.
UNITÉ DE DOCTRINE -CONTINGENCY OF PRACTICE? [...] 275 Fig. 4 The catholic town church of Baden, façade after restoration by Linus Birchler in 1936/37 (reprinted from Birchler, 1960 In 1957 Birchler was also involved in the restoration of the little parish church in Bütschwil. This church had been built in 1886 according to a neo-romanesque design by local architect August Hardegger  and was considered of little historic or aesthetic value. In this project, Birchler was involved privately and not in his capacity as president of the Federal Comission. Free from public obligations, he considered the little church a testing ground for his method of restoration design. As in the Augustinerkirche project, Birchler opted for a sober interior and a flat wooden ceiling (Birchler, 1957a).

Conclusion
The objective of the rising number of charters and principles for the preservation of cultural heritage in the twentieth century was to articulate and impose basic standards and a common code of ethics, both on international and national level. Accordingly, these documents are often considered as visionary provisions and mainly discussed in regard to their prospective influence. From a different perspective, the guidelines constitute historic documents reflecting in retrospect experiences gained in past restorations and generalizing gained insights and experiences in dealing with particular objects. Thus, the theoretical framework of building heritage conservation is not necessarily a predefined set of tenets and axioms with potentially universal significance, but a result of particular challenges and practices bound in time and place (c.f. Schmid, 1993). As in regard to the Charter of Venice, one can hardly find a sentence in Birchler's principles in opposition to our current conservation ethics. Yet the supposed lasting validity of this theoretical foundation of conservation theory is questionable in regard to the actual practice at that time, which will hardly find our consent. The longevity of the principles in spite of changing attitudes was not the result of lacking interest in theoretical reflection, but of the original text's vagueness in regard to concrete practical challenges. The guidelines could and have accommodated a wide range of different and contradictory approaches. In retrospect, the dominant practice in Swiss building heritage conservation at the middle of last century could neither accommodate the historic imitation, nor the fragmented, the opaque, or the simultaneity of temporal layers. The "unite de doctrine" demanded "objectivity" in regard to the historic artefacts, meaning the absence of any personal style or preference by the architect, and the comprehensibility and accordance of historic sources. The so-called "schöpferische Denkmalpflege" -both the historicist and modernist creative approach in remodelling the remains of the past -was strongly opposed by Birchler. He and his likeminded group of experts favoured a holistic approach of cautious, impersonal design, so-called "gestaltende Denkmalpflege", as means to authorize a future for the past (Putz, 2015, pp. 224-226). Birchler opted for a popularization of cultural heritage. To be acceptable and understandable to the general public, the artefacts must not show too many layers and contradictions (Birchler, 1954, 39). Today, the alterations and transformations made within the historic fabric at the middle of last century result in manifold problems for preservation. New materials, composites and synthetics, prefabricated building elements and surrogates of all sorts can be found in monuments both new and old. But it is in regard to conservation theory the doings of our predecessors pose even bigger challenges. Indeed, in their current state, the aforementioned churches less represent the 12th, 15th or 19th century respectively, but authentic models of mid-20th century art history. They stand for the specific understanding this period had regarding the true and original image and design intent of the respective objects. Identifying and assessing the deficiencies and sacrifices of past restorations must yet not result in a reduction of listed monuments. Rather, it is only through critical reflection of past practices we in fact establish the works of old as our heritage.