*** This News & Views piece comments on Goris, Movshon & Simoncelli, 2014 - Partitioning neuronal variability. *** Responses of cortical neurons appear to be notoriously noisy. Even with repeated presen- tations of the same visual stimulus, we rarely observe the same spike train twice. This high degree of variability, which is often correlated amongst pairs of neurons, has fascinated neu- roscientists for decades. Is it noise, arising from stochastic features of neural architecture, or does it reflect meaningful, yet complicated, signals that we simply do not understand? Thus far, it is still not entirely clear what causes the observed neuronal variability. Moreover, we do not even have simple, parsimonious models to describe it appropriately. A study by Goris, Movshon and Simoncelli in this issue of Nature Neuroscience fills this latter gap and proposes a simple conceptual model that provides a new view on cortical response variability.