 Markosian’s maneuver is possible because in giving the rate of one process of change by appeal to a second process of change we are not saying what makes it the case that the first change occurs at the rate it does. What makes it the case—what are the ontological grounds of the fact—that the car travels at 40 mph? Not that an hour of time passes while the car moves a distance of 40 miles, for that is merely a re-description of the fact in question: a way of describing the rate. In the case of time itself, defenders of the view that time passes may plausibly claim that what makes it the case that time passes is simply the nature of time: that it is in its nature to pass at the rate it does. It doesn’t pass at the rate it does because of some relation it stands in, either to ordinary processes of change or to a second temporal dimension. Such relations allow us to informatively state the rate of change, they do not provide the grounds for it.