 Dewey’s choice of impulse as the original motor source of conduct contrasts with conventional desire-based psychology in two ways. First, it takes activity rather than rest as the default state of human beings. Desires are defined by the states of affairs they aim to achieve. On this model, action needs to be inspired by an idea of some deficit. Once the deficit is repaired, the desire is fulfilled, and the organism returns to a state of rest. Dewey observed that this model does not fit what we know about children. They are constantly in motion even when they achieve no particular purpose in moving. They don’t need any end in view or perception of external lack to move them (HNC 118–9). Second, impulse psychology stresses the plasticity of the sources of conduct. Desires are fixed by their ends. Impulses can be directed and shaped toward various ends. Children’s primitive impulses to move their bodies energetically can be directed, through education, toward the development of socially valued skills and interpersonally coordinated activity (HNC 69–75).