There are times when I think that there is a philosophical component of mathematics. Mathematics can be thought as an art and/or as a science.
Given that the variable is for time, the sine and cosine functions can be thought of as symbols of karma or even economic cycles. There are good times, bad times and so on. The featured image is not the most accurate model of life but it gives a decent representation of it.
The featured image is from http://www.math.utah.edu/~pa/math/trig/G1.gif.