This chapter discusses the brain-in-a-vat thought experiment and attempts to determine what needs to be specified so that one can properly imagine a brain in a vat. Daniel Dennett notes that philosophers often fail to set up their intuition pumps properly by failing to think carefully about the requirements and implications of their imagined scenarios. His suggestion is considered here and a careful look at the brain-in-a-vat thought experiment is proposed. The chapter puts the thought experiment to new use, namely, to address the biology of consciousness and to develop some new considerations in support of the enactive approach in cognitive science. Its main argument is that the brain-in-vat thought experiment, when spelled out with the requisite detail, suggests precisely that the body is not merely causally enabling for consciousness, but also constitutive.