On this sheet Leonardo depicts horses in a variety of extreme attitudes, and five vignettes of St George fighting a dragon serve the same purpose, giving a context to the twisting of the horse away from the monster. The notes on this sheet and on RCIN 912363 show that Leonardo’s concern was the range of movements attainable by animals: ‘Of flexion and extension. The lion is prince of this animal species because of the flexibility of its spine’; and ‘Serpentine movement is the principal action in animals, and is double, the first along its length and the second across its width.’ In a notebook of c.1513–14 Leonardo proposed ‘a treatise on the movements of animals with four feet, among which is man, who in his infancy crawls on all fours’. That was perhaps displacement activity for Leonardo’s stalled work on human anatomy, and there is no sustained evidence, beyond these drawings of a few years later, that he developed a treatise on animal motion in any detail. Text adapted from Leonardo da Vinci: A life in drawing, London, 2018