“To the degree that a man possesses a vivid ideal of the good life, submerges himself in the sea of human misery and endeavors to alleviate suffering, kindles imagination in hours of silence and by visions of beauty, and follows the noblest personality into the presence of a loving, suffering Father—to the extent that he lives meaningfully, he will be convinced of sin and cry aloud for deliverance.”

In Encyclical Letter Spe Salvi http://www.vatican.va/holy_father/benedict_xvi/encyclicals/documents/hf_ben-xvi_enc_20071130_spe-salvi_en.html (30 November 2007)
2007

The Tragic Sense of Life (1913), IX : Faith, Hope, and Charity
Context: Suffering is a spiritual thing. It is the most immediate revelation of consciousness, and it may be that our body was given us simply in order that suffering might be enabled to manifest itself. A man who had never known suffering, either in greater or less degree, would scarcely possess consciousness of himself. The child first cries at birth when the air, entering into his lungs and limiting him, seems to say to him: You have to breathe me in order to live!

Reb Saunders to Reuven Malter when talking about when Daniel was younger (p. 286)
The Chosen (1967)

Source: UnWholly

The Eighth Revelation, Chapter 20

Manchester Guardian, 2 July 1934, quoted in Bernard Donoughue and George Jones, "Herbert Morrison: Portrait of a Politician" (Phoenix Press, 2001), p. 184.

Quoted in Oxford Dictionary of Medical Quotations by Peter McDonald (Oxford University Press, 2004), p. 9 https://books.google.it/books?id=MuTnCwAAQBAJ&pg=PA9.
Attributed

Variant: I learned this, at least, by my experiment: that if one advances confidently in the direction of his dreams, and endeavors to live the life which he has imagined, he will meet with a success unexpected in common hours.
Source: Walden: Or, Life in the Woods