This chapter describes sentience, or sensory awareness, as the first subdomain of psychology. Its unique features—secondary sense qualities, raw feel, and the brief temporality of presence among them—lead to speculations that sentience is primordial and a property of living cells long before the evolution of nervous systems. With reference to the early evolution of life forms, it is argued that nervous systems do not produce sentience, but merely process it. It is also argued that the final explanation of sentience is probably to be found in the world of quantum mechanics, which leads to the admission that it is an understatement when philosophers have called sentience the hard problem.