How much about our interactions with - and experience of - our world can be deduced from basic principles? This talk reviews recent attempts to understand the self-organised behaviour of embodied agents, like ourselves, as satisfying basic imperatives for sustained exchanges with the environment. In brief, one simple driving force appears to explain many aspects of action and perception. This driving force is the minimisation of surprise or prediction error that - in the context of perception - corresponds to Bayes-optimal predictive coding (that suppresses exteroceptive prediction errors) and - in the context of action - reduces to classical motor reflexes (that suppress proprioceptive prediction errors). We will look at some of the phenomena that emerge from this single principle; such as the perceptual encoding of sensory trajectories (bird song and action perception). These perceptual abilities rest upon prior beliefs about the world – but where do these beliefs come from? I will finish by discussing recent proposals about the nature of prior beliefs and how they underwrite the active sampling of the sensorium. Put simply, to minimise surprising states of the world, it is necessary to sample inputs that minimise uncertainty about the causes of sensory input. When this minimisation is implemented via prior beliefs - about how we sample the world - the resulting behaviour is remarkably reminiscent of searches of the sort seen in exploration and visual searches.