From his The Shaking of the Foundations:

66506_10151313191256554_161490691_nIt happens, or it does not happen. And certainly it does not happen if we try to force it upon ourselves, just as it shall not happen so long as we think, in our self-complacency, that we have no need of it. Grace strikes us when we are in great pain and restlessness. It strikes us when we walk through the dark valley of a meaningless and empty life. It strikes us when we feel that our separation is deeper than usual, because we have violated another life, a life which we loved, or from which we were estranged. It strikes us when our disgust for our own being, our indifference, our weakness, our hostility, and our lack of direction have become intolerable to us. It strikes us when, year after year, the longed-for perfection of life does not appear, when the old compulsions reign within us as they have for decades, when despair destroys all joy and courage. Sometimes at that moment a wave of light breaks into our darkness, and it is as though a voice were saying: You are accepted, accepted by that which is greater than you, and the name of which you do not know. Do not try to do anything now; perhaps later you will do much. Do not seek for anything, do not perform anything, do not intend anything. Simply accept the fact that you are accepted! If that happens to us, we experience grace. After such an experience we may not be better than before, and we may not believe more than before…