Trees belong to the largest living organisms on Earth and plants in general are one of our main renewable resources. Wood as a material has been used since the beginning of humankind. Today, forestry still provides raw materials for a variety of applications, for example in the building industry, in paper manufacturing and for various wood products. However, many parts of the tree, such as reaction wood, branches and bark are often discarded as forestry residues and waste wood, used as additives in composite materials or burned for energy production. More advanced uses of bark include the extraction of chemical substances for glues, food additives or healthcare, as well as the transformation to advanced carbon materials. Here, we argue that a proper understanding of the internal fibrous structure and the resulting mechanical behaviour of these forest residues allows for the design of materials with greatly varying properties and applications. We show that simple and cheap treatments can give tree bark a leather-like appearance that can be used for the construction of shelters and even the fabrication of woven textiles. This article is part of the theme issue ‘Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 1)’.

In the course of the nineteenth century, the development of non-Euclidean geometries and topology led to wide-ranging discussions on the foundations of mathematics. The new mathematical objects and the accompanying disputes also became a source of fascination for literature. A paradigmatic instance of this is the French writer and theorist Paul Valéry (1871-1945), whose Cahiers (1894-1945) show a constant preoccupation with mathematical problems. What is remarkable here is the fundamental significance Valéry ascribes to mathematics for his own work. Initially, he searched in topology for a tool to advance his reflection on psychology. Although this project ultimately failed, mathematics became for Valéry an ideal—since "operative"—mode of writing, one against which to measure his own literary writing and note-taking. However, the result of this formalization, which he pursued over decades, was neither mathematic literature nor, indeed, literary mathematics, but a form of writing that had a significant effect upon the twentieth-century understanding of literature: the aim of producing a finished work was shifted into the background to make room for writing as a "life-form."

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