In the process of making bedsteads, Plato claimed, makers look towards the ‘idea’ of the bed. But what is that idea? Two candidates come to mind: shape and purpose. The fact that we identify objects of very different shape, not even involving a bedstead, as beds seems to render purpose conceptually superior. But, then, what is a bed’s purpose? An obvious response appears tobe: lying down and sleeping. Yet, first, beds are not needed for that. Secondly, precisely when a bed is slept on, it is not perceived as a design object. Thirdly, beds constitute a kind of existential furniture, associated with giving birth, making love, suffering illness and dying. All such issues humans really care about, however, are strikingly indifferent towards the design of beds. As elsewhere, the maxim that form follows function fails. Design thinking might rather make headway when beds are conceived of as peculiar spaces within spaces.