Galileo compared the periodic motion of a pendulum, or the diminishing level of water in a chamber, to the motion of some other object, such as a rolling ball on an incline plane or horizontal surface. Technically motion is the change in position of an object in space. This change of position is called displacement. The displacement of the clock is compared with the displacement of some other object. Galileo puts the object displacement in the numerator and the clock displacement in the denominator. By counting the periodic displacement changes in the clock we have a means to specify the elapsed time or change in time on a discrete or continuous basis. Time is the inverse of frequency of a resonant or rotating system. The displacement has cycles or oscillations that map to the trigonometric functions on the unit circle. So the resonance property of nature, the capacity to compare displacement, the ability to make ratios, and human memories give us the concept of elapsed time. I would argue that resonance is a property of eternal nature and time is a human invention. Also we age and die. Many, but not all, natural events seem to be irreversible from our perspective. Thus we imagine the arrow of time from the Big Bang to some ultimate state or the Bang Bang Bang theory of an expanding and collapsing universe, etc. But eternal nature exists independent of our human perceptions of time! The observer and the observed both have a property of eternity which transcends time!

Galileo compared the periodic motion of a pendulum, or the diminishing level of water in a chamber, to the motion of some other object, such as a rolling ball on an incline plane or horizontal surface. Technically motion is the change in position of an object in space. This change of position is called displacement. The displacement of the clock is compared with the displacement of some other object. Galileo puts the object displacement in the numerator and the clock displacement in the denominator to define speed. He defines accleration as the change of speed. 

By counting the periodic displacement changes in the clock we have a means to specify the elapsed time or change in time on a discrete or continuous basis. Time is the inverse of frequency of a resonant or rotating system. The resonant displacement has cycles or oscillations that map to the trigonometric functions on the unit circle. The resonance property of nature, the capacity to compare displacement, the ability to make ratios, and human memories give us the concept of elapsed time. 

I would argue that resonance is a property of eternal nature and time is a human invention. We age and die. Many, but not all, natural events seem to be irreversible from our perspective. We imagine the arrow of time from birth to death or from the Big Bang to some ultimate state. We also imagine the Bang Bang Bang theory of an expanding and collapsing universe or the invisible multiverse, etc. But eternal nature exists independent of our human perceptions of time! The observer and the observed both have a property of eternity which transcends the perception of time!