Once Tanguy settled into his mature manner in the late 1920s, he spent the rest of his career exploring and elaborating it rather than departing from it, working in an unpremeditated way directly on the canvas rather than from preparatory drawings^[1]. André Breton, writing in the same period Tanguy's work matured, argued that before Tanguy the painted object, however strangely treated, had always remained recognisable and a prisoner of its own identity; with Tanguy's work, Breton wrote, viewers entered a world of complete indeterminacy for the first time, where no actual, fixed appearances were promised^[5].

Tanguy's father died when he was eight, and his brother was killed in action during the First World War. After school he joined the merchant navy and was later conscripted into the French army in Tunis, where he met the poet Jacques Prévert; back in Paris, the house they shared with the writer Marcel Duhamel became a gathering place for artists and writers^[2]. In 1923 he saw Giorgio de Chirico's Le Cerveau de l'Enfant in a gallery window and decided on the spot to become a painter, despite having no formal training. He met Breton in 1924 and joined the Surrealist group the following year; Breton later wrote, 'What is Surrealism? It is the appearance of Yves Tanguy,' gave him a contract to paint twelve works a year, and described the strange creatures that populate his canvases as 'subject-objects'^[2].

A 1930 trip to Africa changed the character of Tanguy's imagery. Vegetal forms gave way to mineral ones, and he began incorporating the geological formations he had observed there: dolmens and menhirs, stone remnants of prehistoric ages, and fossilised bone, smoothed and tinted within the dream spaces of his canvases^[1]. The paintings that followed this trip are sometimes grouped as les coulées, or flowing forms, for their molten, viscous character, built with geometric precision and a minutely detailed, almost academic technique in which careful modelling gives the forms real plastic solidity even as they melt, ooze or collapse into one another^[3].