It is very much a statistical concept looking at economic aggregates and sectors. It is meaningless to speak of cycles that begin and end. That is the fallacy of the chicken or the egg. The reason is that in dynamic systems there are many overlapping cycles. People are born and they die, but as a general rule the population as a whole grows.
People individually save today so that they can spend later.
For the economy as a whole, spending and saving are going on simultaneously. Loans are being granted and loans are being repaid, all at the same time. Zeno knew quite well that Achilles would indeed overtake the tortoise. That discovery occurred twenty-three hundred years later by Galileo, Newton and their colleagues. Through exhaustive experimentation mostly with the inclined plane, but some from Pisa's leaning tower-Galileo proved that the speed of a falling object is proportional to the TIME it has fallen, not the distance it has fallen.