A boy starts out full of energy and confidence, running with open arms toward the mountains, so strong that even the wind seems to give way to him. The poem then turns. His arms shake, he loses himself, and he comes upon an image that stops him. He calls it a "wonderful creature" and moves closer, only to find himself caught in what the poem calls "the beast's nest."
Read plainly, this looks like a story about falling in love too fast. The boy imagines a "perfect future" in a rush, grows impatient, and then angry. The last line delivers the shock: what he took for love was dressed up, with scars hidden by makeup. The poem suggests the person, or the idea of love, was not what it appeared to be.
The mood moves from joyful and carefree to dreamy, then uneasy, and finally bitter and disillusioned. The speaker seems to feel both pity and warning toward the boy, whose hopes outran what he could actually see.