timelets

One of the most significant consequences of the introduction of the clock-and, with it, the quantitative view of duration-to the West has been the evolution of an abstract conception of time there.
...
The abstract conception of time is at the basis of the modern notion of duration, which is essentially what we measure when we use the stopwatch, the parking meter, or the egg timer.

--- Evitar Zerubavel. Hidden Rhythms, 1985.

The invention of the mechanical clock made the duration aspect of time monoidable. As a result we can map it to any other measurable entity, e.g. money, effort, skill, etc.