August 10

The more difficulties one sees in the world the more perfect one becomes. The more you plough and dig the ground the more fertile it becomes. The more you cut the branches of a tree the higher and stronger it grows. The more you put the gold in the fire, the purer it becomes. The more you sharpen the steel by grinding the better it cuts. Therefore, the more sorrows one sees the more perfect one becomes. That is why, in all times, the Prophets of God have had tribulations and difficulties to withstand. The more often the captain of a ship is in the tempest and difficult sailing the more greater his knowledge becomes. Therefore I am happy that you have had great tribulations and difficulties . . . Strange it is that I love you and still I am happy that you have sorrows. 
('Abdu'l-Baha, Star of the West, vol. XIV, no. 2, p. 41, quoted by the Universal House of Justice in a letter written on its behalf to an individual believer, 23 October, 1994)