The glider is always sliding "downhill", the updrafts, thermals, ridge lift,
all just change the height of the hill. The wing just changes the slope of
the hill, a 1-26 has a steep slope and an ASH-25 has a shallow slope. We
are all sliding downhill when we soar.

What if the glider isn't falling, but moving at a constant altitude
while ridge or wave soaring? What powers it then? I think it's the wind,
like a sailboat.