Oak. . . lasts for an unlimited period when buried in underground structures. . . . when exposed to moisture. . . it cannot take in liquid on account of its compactness, but, withdrawing from the moisture, it resists it and warps, thus making cracks.
Fear is the workout we give ourselves imagining what will happen if things don't work out. . . . Worry is our effort to imagine every possible way to avoid the outcome that is causing us fear, and failing that, to survive the thing that we fear if it comes to fruition.