The metaphor of an *attention economy* has become so (0) ENTRENCHED in commentary on digital life that its peculiarities are easily overlooked. Attention is, like any economic resource, finite; unlike most economic resources, it cannot be stored, transferred, or in any meaningful sense. Each minute unspent is lost absolutely, and no of future attention can compensate for the past minute's having escaped notice. This peculiarity gives the market for attention a character to that of any other market. Producers cannot build up inventory; consumers cannot for later. The result is a pattern of competition in which every available second is contested in real time, and the winners are typically those whose products most effectively to the involuntary mechanisms of human perception — novelty, motion, faces, conflict. These products need not be good in any substantive sense; they need only the arms race of salience better than their competitors. An ecosystem organised around such selection pressures will, over time, a particular kind of content: content optimised for capture rather than for contemplation, for response rather than for reflection. Whether such an ecosystem is compatible with the conditions that serious thought is a question our civilisation has only begun to ask.