Extraordinary experiences in meditation

Above all, it is not necessary that we should have any unexpected,
extraordinary experiences in meditation. This can happen, but if it
does not, it is not a sign that the meditation period has been
useless. Not only at the beginning, but repeatedly, there will be
times when we feel a great spiritual dryness and apathy, an
aversion, even an inability to meditate. We dare not be balked by
such experiences. Above all, we must not allow them to keep us from
adhering to our meditation period with great patience and fidelity.
- Dietrich Bonhoeffer (1906-1945), In "Life Together"