The exhibition Calder-Picasso at the de Young museum presents a compelling visual conversation centering around the two artists’ exploration of the void, or the absence of space, which both defined from the figure through to abstraction. Calder and Picasso wanted to present or represent non-space, whether by giving definition to a subtraction of mass, as in Calder’s sculpture or by expressing contortions of time, as in Picasso’s portraits.