The human heart is like india-rubber; a little swells it, but a great deal will not burst it. If "little more than nothing will disturb it, little less than all things will suffice" to break it. As in the outer members of our frame, there is a vital power inherent in itself that strengthens it against external violence. Every blow that shakes it will serve to harden it against a future stroke; as constant labour thickens the skin of the hand, and strengthens its muscles instead of wasting them away: so that a day of arduous toil, that might excoriate a lady's palm, would make no sensible impression on that of a hardy ploughman.
Anne Brontë, Agnes Grey
agnes-grey, heart, perseverance