"...crouching under its load...”: Under such “hostile” conditions, the Torah and its commandments become a burden to the body, even though the Torah is in a “space of it’s own”, given to man specifically to refine and elevate the physical. Not recognising what is for its own benefit, the body resists the “load.”
One's first inclination may be "to refrain from helping him", to negate the material – to do away with the physicality of things. Says the Torah "nevertheless, you should help him" - cure the “donkey” of its folly, refine and develop its tremendous potential.
How does one do this? First, make the body aware "that he's a horse", bring it to recognise the coarseness of its undeveloped state. Then, "whip the horse so that he should cease to be a horse," directing its energies and resources to positive and G-dly ends."