In early 1966, Oxenaar’s emergency warning about the condition of the building suddenly becomes urgent. According to Oxenaar, the paint layer of the paintings on display, including ‘some of Vincent van Gogh’s best works’ is beginning to ‘peel’. Oxenaar believes that the cause is the lack of a climate control system. He wants to purchase an ‘air conditioning system’ that ‘can be incorporated into the building in an aesthetically pleasing manner’, but emphasizes that ‘the only real solution for the deteriorating structural condition of the museum lies in a thorough overhaul of the foundations’.

To mark the tenth anniversary of H.P. Bremmer’s death in January, Oxenaar organizes a commemorative exhibition. ‘Given that the entire collection of the museum […] is already a monument to Dr Bremmer’s work and insight as an art connoisseur’, the exhibition focuses on Bremmer’s own work as an artist and the work of his friends and students, including Bart van der Leck, Jan and Charley Toorop, John Rädecker, Joseph Mendes da Costa and Floris Verster. The exhibition comprises work from the museum’s own collection supplemented with works on loan from the Bremmer family. The opening on 5 March is attended by Bremmer’s sons and daughter, Mrs Kröller-Müller’s granddaughter and the daughter of Bart van der Leck, among others.

After extensive consultation and walking tours of the grounds, agreement is reached with the management of De Hoge Veluwe National Park on the new boundaries of the sculpture garden. In the annual report, Oxenaar praises the willingness of the National Park: ‘Without this concession, whereby the unity of the Park and Museum, as Mrs Kröller-Müller always regarded it, was adopted as the point of departure, this expansion of the sculpture garden would not have been possible.’

The sculpture garden is expanded from 4 to 9 hectares and thus becomes ‘the size of a large municipal park’. The garden now also includes a rhododendron forest and extends to the foothills of the Franse Berg. The three ascending stairways make it possible to take a tour over the crest of this ridge. ‘The network of paths was kept as simple as possible. The intention is that people can move freely through the grounds.’ The new section is wilder and ‘less cultivated’. The fields are sown with wild grass and will not be mowed. Also, a ‘beautiful little valley hidden between the hills has been created’, bordered by the thickly wooded slopes of the Franse Berg.

The expansion of the sculpture garden is opened with the retrospective exhibition Beelden in ijzer en staal (Sculptures in iron and steel) with work by the recently deceased American sculptor David Smith.

On Oxenaar’s initiative, the private collection of Robert and Lisa Sainsbury from London is exhibited in the summer. It is the first time that the ‘treasures they have collected in more than thirty years of careful selection’ are shown publicly. The collection consists of large groups of works by Henry Moore, Alberto Giacometti and Francis Bacon, as well as 120 sculptures and objects from Africa, Oceania, North America, Mexico, Egypt, China, Greece and Italy. The interior designer Kho Liang Ie is responsible for the layout of the exhibition. Oxenaar writes in the catalogue: ‘From the outset it was clear to all parties that there was a kinship between the hosting and the visiting collection’.

After three years as director, Oxenaar formulates his vision for the museum. He finds the ‘encounter between nature and art’ determinative for the character of the Rijksmuseum Kröller-Müller, ‘where one should first and foremost find peace, intimacy, and direct aesthetic experience without this leading to the atmosphere of an art temple or a meditation centre’. The guiding principle in the development of presentations is the ‘idea of community, which was the starting point for Mrs Kröller’. The relationship between nature, visual art and architecture is also the central tenet therein.

Oxenaar also looks to Helene for the acquisition policy. ‘The qualitative standard achieved by Mrs Kröller must remain the benchmark for the level at which we proceed.’ But precisely where it concerns ‘contemporary sculpture and drawing at an international level’, it is ‘once again clear […] how inadequate the financial resources are that the museum has at its disposal every year’. Nevertheless, he manages to acquire the very important work Abstract figure by Oskar Schlemmer and introduces three new artists in the collection. Concetto spaziale nature by Lucio Fontana, Two vertical, three horizontal lines by George Rickey and Walking man II (1960) by Alberto Giacometti are placed in the sculpture garden.

The summer of 1967 is dominated by two duo exhibitions. The first is of the British artists Anthony Caro and Eduardo Paolozzi. ‘We show their work at the same time because each in their own way has been highly influential in the development of the latest British sculpture’, according to Oxenaar. ‘Together they form a small, but important intermediate generation that has made the transition from old to new possible.’ Then it is the turn of the Swiss sculptors Jean Tinguely and Bernard Luginbühl, both of whom show recent work.

Thanks to ‘the exceptional generosity’ of Barbara Hepworth, Oxenaar is able to acquire seven of her sculptures, while she also donates the bronze Oval form (Trezion). This means that the important British artist is represented in the museum with 12 works, which together provide a good impression of her development. This method of acquisition ‘was always and still remains a policy principle in this museum’ according to Oxenaar, ‘which creates nuclei that have a binding effect in the totality of the collection’. The sculptures are placed in the Rietveld pavilion, which now creates a permanent and ‘fascinating interplay of architecture and sculpture worthy of Rietveld himself’.

When Hammacher resigns in 1963, he is given the opportunity to have his portrait made by an artist of his choice. The commission is given to the sculptor Hans Verhulst. Four years later, the bronze bust is ready. Oxenaar writes on behalf of the staff that they are ‘delighted […] that the portrait has now assumed its place in the museum’. With the delivery of the artwork, Hammacher also vacates his position as advisor for the sculpture garden. He does, however, remain active as trustee of the Kröller-Müller Foundation.

This year the museum acquires four constructivist works: Structurist work no. 28, Red Wing by Charles Biederman, Relief construction by Anthony Hill, Volume Suspendu by Jésus Raphael Soto and Reliëf spatio-temporel no. 17 by Jean Gorin. In return for the Van Gogh exhibition held in Belgrade, the Yugoslav government presents the museum with Bird 3 by Oto Logo and Metal sculpture by Dusan Dzamonja. Piet Sanders, trustee of the Kröller-Müller Foundation and member of the Oversight Committee, donates Ant castle 8 by Ryokichi Mukai and Tower by Hubert Dalwood.