Tests: Potentially a healing medicine

In a prayer, ‘Abdu’l-Bahá avers how we as humans on earth are "encircled with pain and calamities and are environed with hardships and trouble," and that man is here attacked by "every trial" and assailed by "every dire adversity...like unto the assault of a serpent." Then where is refuge to be found? In our Lord, the Merciful One:

O my Lord! Thou knowest that the people are encircled with pain and calamities and are environed with hardships and trouble. Every trial doth attack man and every dire adversity doth assail him like unto the assault of a serpent. There is no shelter and asylum for him except under the wing of Thy protection, preservation, guard and custody.

O Thou the Merciful One! O my Lord! Make Thy protection my armor, Thy preservation my shield, humbleness before the door of Thy oneness my guard, and Thy custody and defense my fortress and my abode. Preserve me from the suggestions of self and desire, and guard me from every sickness, trial, difficulty and ordeal.

Verily, Thou art the Protector, the Guardian, the Preserver, the Sufficer, and verily, Thou art the Merciful of the Most Merciful.

—‘Abdu’l-Bahá, BP 136

According to the Hidden Words of Bahá'u'lláh, the "fire" of calamity is in reality "light and mercy", and He thus commands us to "hasten" unto the former:

O SON OF MAN! My calamity is My providence, outwardly it is fire and vengeance, but inwardly it is light and mercy. Hasten thereunto that thou mayest become an eternal light and an immortal spirit. This is My command unto thee, do thou observe it.

In another thought-provoking passage, ‘Abdu’l-Bahá states:

Men who suffer not, attain no perfection. The plant most pruned by the gardeners is that one which, when the summer comes, will have the most beautiful blossoms and the most abundant fruit.

The labourer cuts up the earth with his plough, and from that earth comes the rich and plentiful harvest. The more a man is chastened, the greater is the harvest of spiritual virtues shown forth by him. A soldier is no good General until he has been in the front of the fiercest battle and has received the deepest wounds.

The prayer of the prophets of God has always been, and still is: Oh God, I long to lay down my life in the path to Thee! I desire to shed my blood for Thee, and to make the supreme sacrifice.

- Paris Talks 51 (emphasis is mine)

The highest spiritual state we can yearn for is perhaps illustrated by the following potent prayer revealed by Bahá'u'lláh where He implores God to "send down upon us...that which will enable us to draw nigh unto [Him]" (however "calamitous" and "painful" that may be).

O Thou Whose tests are a healing medicine to such as are nigh unto Thee, Whose sword is the ardent desire of all them that love Thee, Whose dart is the dearest wish of those hearts that yearn after Thee, Whose decree is the sole hope of them that have recognized Thy truth! I implore Thee, by Thy divine sweetness and by the splendors of the glory of Thy face, to send down upon us from Thy retreats on high that which will enable us to draw nigh unto Thee. Set, then, our feet firm, O my God, in Thy Cause, and enlighten our hearts with the effulgence of Thy knowledge, and illumine our breasts with the brightness of Thy names.

—Bahá’u’lláh, BP 191

The state of the one offering this prayer must be one of complete detachment from the comforts and desires of this world, otherwise it will have no effect. With daily practice and discipline, such a purified condition can be gradually attained by the wayfarer in God's path. The Seven Valleys of Bahá'u'lláh illustrates the different stages through which a true seeker must pass on his spiritual journey.