Mathilde Interview | L'Observatoire International

In Conversation with Mathilde Rouiller, art and research at L'Observatoire International

July 3, 2026

You have been in dialogue with Hervé Descottes and L’Observatoire International for nearly ten years. How did this collaboration begin, and how has it developed over time?

Mathilde Rouiller: I met Hervé in 2016 while I was finishing the Graduate School of Arts and Sciences at Columbia University. I was going back and forth between Ecole des Hautes Etudes in Paris and several research fellowships in American universities. While I was finishing my master in performance studies and philosophy/anthropology, he asked me to stage the opening ceremony for the re-enlightment of several bridges, and so with my tiny experience as a stage director and scenographer I created an overall concept with lighting.

This opening ceremony never took place but this was the beginning of a great collaboration that has now been on-going for ten years. I started working with the company from Paris, and then in September 2017 I joined the New-York office for a year. Since then, we have been collaborating on the research and development of multiple concepts for diverse architectural lighting projects. I did not know anything about lighting at that time, so I was thinking of concepts in terms of philosophy and artistic, and it created a great conceptual addition at the very beginning of very special projects. For several years now, we have been working on an on-going research project about a glossary of light, and I jump-in for really high-end projects.

Herve’s references are mostly about arts, architecture, and a very instinctive sense of philosophy, so it has been a very beautiful conversation between us. I see it mostly as an exchange of ideas, and this is the way I prefer working on a project in general, when there is a real dialogue with the creative, the designers. This dialogue fosters the strongest and most coherent concepts.

How is the notion of sustainability reshaping the way we think about lighting today?

MR: With the climate crisis and other structural issues now shifting the world, our cognitive vision is on the edge of something very new: we need to care for a very specific register of attention and attachment. In two decades, we went from a logic of preservation and restoration to a logic of regeneration. This is something that is way wider than the design and architectural field, but a more way to rethink society at its very different levels. It has come from ecological philosophy.

Thinking this way shifts our mind, but also refreshes our logical constructions, our paradigms to envision the world. Resources but also notions such as inclusivity can be thought in terms of care, and not in terms of erasing and this is very interesting to apply to lighting design or the creation of moving images in general. Imagine we would think of darkness as a rarified resource that needs to be taken care of, how would the creative act of lighting be rethought ?

Of course, it is not new for lighting designers to lower the light volume, I always heard Hervé asking for warmer, low light, less intense lighting but we can now link that to a more caring and sustainable way of lighting.

The recent workshop developed with the University of Bologna and the TALEA project explored new ways of engaging with the city through light. What were the main ideas behind this initiative?

MR: During this 4-month long workshop with the University of Bologna, as part of the TALEA project (a European initiative), we developed with the students and their mentors lighting cells that were chosen through three experiments, in accordance with a wider work made with the municipality and architects. We started with a lecture and the main focus was on regeneration.

We wanted them to think of light materiality, of course, but before understanding what Hervé calls the “why”, which is the context and the philosophical concept behind it. The plays of the lighting principles come after. It is the same in theater : you would never think of the lighting or the actor plays, so the activation before imagining the structure and the story behind, unfolds. From the workshop, the students develop a great preliminary lighting concept, they emphasize and develop on the notion of « heritage » both in architecture (e.i. : the galleries, the park, etc.) and ecological ways (e.i. : Bologna butterflies). This interweaving was very interesting for us because it helps to connect with the city in a different way. We were also trying to connect to the sky at night, and to create the idea of dark sky - even if this is not really possible in cities for now - is a first step to envision sustainable lighting design.

How does a philosophy for light unfold in lighting design, and how can it shape new ways of imagining more desirable futures for our cities and environments?

MR: Like other animals, your vision at night adapts, so what is interesting is to make your eyes focus on the darkness and not on the artificial light, this is how you start to rebuild the notion of contrast, and of brightness. Your neuronal and optic connections cannot do it if there is too much glare. This is something very important that Hervé made me understand, and as a performer and someone who thinks in terms of staging that is a major notion. And for me, lighting design is like a theater or movie scene, so you kind of come with the same affective and perceptive ideas that you will try to recreate with the artificiality of a stage, a black box.

And so, you can develop new narratives : you can envision your relationship to the dark sky and the darkness not as something that is scary or negative, but as a rarified ressource, you can try to implement lighting that shares its source with multiple other living elements. This is an important change of paradigm that will affect your design. And even if this is very speculative for now, envisioning it allows your brain and your creativity to think of new imaginaries and so getting used to it cognitively speaking. We play exactly the same with lighting design. This is why it is very important to integrate lighting principles but also to shift organically into the night. You kind of follow and escort the eyes into the night

Lighting is almost something alive, so you have to create systems that answer to each other in their relations, to be sure they will adapt to different situations. It is like staging your atmosphere, but also creating scripts. My work focuses on staging abiotic elements such as light, and this is why making place for speculative narratives that involve it help to foster our imagination and desirable futures.

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