Every Christian is subjected to some kind of test: one with poverty, another with sickness, a third with various bad thoughts, the fourth with some type of misfortune or humiliation, while another, with perplexities. This tests the strength of one’s faith, and hope, and love for God, that is, shows the person’s inclinations, his attachments, whether he aims for sorrows or is still affixed to earthly things.
So that through these trials a person-Christian himself could see in what position he is in, what his disposition is, and involuntarily humble himself. Because without humility, as all the holy fathers of Godly wisdom confirm in one voice, all our works are unsettled. Even the free will of Angels was tested. If the Heavenly dwellers could not escape the test, then more so must the free will be tested of those living on earth.
Elder Ambrose of Optina