Fifty years ago Anthony Radcliffe wrote that “Donatello was … the first sculptor of the Renaissance to realise the potential of the classical form of the free-standing figure,” an uncontroversial assessment at the time and one that would almost certainly achieve broad consensus among scholars today.1 The major events in the artist’s life that preceded this are well known. In the 1420s, Donatello was already “confronted … with the problems of pose and ponderation peculiar to free-standing statuary” while preparing the figures of the Siena Baptistery font and presumably studying ancient statuettes.2 In the 1410s and 1420s, the artist made monumental statues for Orsanmichele and continued work on others for the bell tower of Florence Cathedral (see, e.g., Fig. 84), and in 1432–3 he encountered the antiquities of Rome. Probably in the late 1430s, Donatello created two bronze statues, the David (Fig. 62) and Amor-Atys (Fig. 63), the culmination of his first fifty years of production and innovation and the sculptures that most clearly evince Radcliffe’s assertion.3 The novelty and success of this sculptural type – the freestanding statue – reverberated within the artistic culture of Florence and beyond, and its conceptual claims have influenced art-making arguably to the present. Near the end of his life Donatello designed the Judith and Holofernes (Fig. 64), a freestanding statue group that expanded and deepened the theoretical and spatial challenges posed by his pioneering David and Amor-Atys. This essay attempts to situate these sculptures alongside selective readings of texts by Lorenzo Ghiberti, Lorenzo Valla, and especially Leon Battista Alberti to sketch a notional fifteenth-century theory of freestandingness, the constellation of qualities that characterize figural sculpture made to be experienced in the round.