The combined neuronal activity of two seemingly opposite types of Purkinje cell in the brain's cerebellum has been found to be required to control the jerky eye movements known as saccades in monkeys. See Letter p.439 The Purkinje cells are inhibitory neurons in the cerebellum with a central role in coordinating the body's motor function. It has long been thought that they encode eye motion saccades, but how this is achieved was not known. Recording from Purkinje cells in monkeys, David Herzfeld et al. find that the combined simple-spike responses of bursting and pausing Purkinje cells, but not either population alone, predicted the real-time speed of the saccade. Moreover, when Purkinje cells were organized according to their complex-spike field, the population responses encoded both speed and direction via a gain field.