Although some conceptions of scientific objectivity and observation treat these as virtuous precisely to the extent that the rise above personal or historical bias, the practice and theory of both objectivity and observation have changed through history. Drawing on the work of Lorraine Daston and others, the chapter traces the development of objectivity both in science and theatre through classical and early-modern theatre, in which it was a fairly unimportant epistemic virtue, into the late eighteenth century where objectivity begins to emerge through the idealisations of ‘Truth-to-Nature’ in biology and in literary and theatrical Romanticism. The emergence of modern (‘mechanical’) objectivity, and a new relationship with observation, mark both nineteenth-century science and Naturalist theatre. Making the comparison explains some of the anti-theatrical claims of Naturalist authors and the contradictions of Naturalist practice. As nineteenth-century objectivity’ is superseded, so the theatrical figuration of science gravitates towards areas of ambiguity, chaos and indeterminacy.