Discussions of the nature of time can be enriched using insight from the field of biology. In the evolution of our species, biological timekeeping mechanisms have been honed to a fine point and can accurately adhere to a 24-hour cycle. When considering that these timekeeping mechanisms would only have evolved if they were reasonably accurate, it must be the case that our timekeeping systems are measuring a genuine feature of reality. This thesis explores this idea by discussing the veridicality of the circadian clock and contrasting it with the physiological origin of feelings of duration. As it turns out, duration can not be accounted for by the circadian clock, implying that the felt ‘flow’ of time is a cognitive illusion rather than a feature of objective reality. Given this, our knowledge of biology reconciles best with the Static View (B-theory) of time.