Kondratieff Wave?

Would someone be so kind as to explain how Kondratieff Waves operate to
lowly a undergraduate? While I recognize that they are "40-60 year
business cycles" usually divided into an upsurge a-phase and downtrend
b-phase, I'm a little foggy as to what the exact mechanisms behind this
cycle are. Is it related to the falling rate of profit? Market
saturation? Technological change? Further, whatever lay at the root of
Kondratieff Waves, what makes them cyclical? It seems to me that at least
the dimensions I have listed above are historically contingent and don't
lend themselves to reiteration that the 'wave' terminology applies. In my
mind, the very idea of something being cyclical comes very close to
'naturalizing' a phenomenon. But, I could be, and probably am, very
wrong. Any clarifications would be greatly appreciated.

Anthony S. Alvarez
University of Maryland, College Park
Undergraduate in Sociology and Political Science