Quaestiones Naturales

Is it that the fiery and spiritual power which it hath, being once provoked and (as it were) angered, putteth forth itself so much the more, and mounteth upward? Or is it because the weight, forcing the boughs suddenly, oppresseth and keepeth down the airy substance which they have, and driveth all of it inward; but the same afterwards, having resumed strength again, maketh head afresh, and more eagerly withstandeth the weight? Or, lastly, is it that the softer and more tender branches, not able to sustain the violence at first, so soon as the burden resteth quiet, by little and little lift up themselves, and make a show as if they rose up against it?