Adversity is the road to truth. (Byron)

Suffering is the teacher of life. Balzac)

Adversity inevitably promotes the development of human wisdom mineral deposits. (Dumas)

Unfortunately, it is the best university. (belinsky)

No wise man will deny the exercise value of pain and sadness. (Huxley)

Genius inevitably has obstacles, because obstacles make genius. (Roman? Roland)

A calm lake can't make a thin sailor; Comfortable environment cannot make a great man of the times (lebedev)

The harder life is, the more I feel strong and even smart. Gorky)

Human life is like a flood. It is difficult to drive away beautiful waves without encountering islands and reefs. (ostrovsky

Probably there is no success without suffering.