You feel your strength in the experience of pain.

A strong man doesn't have to be dominant toward a woman. He doesn't match his strength against a woman weak with love for him. He matches it against the world.

The heart may be broken, and the soul remain unshaken.

The discipline of suffering, of great suffering- do you not know that only this discipline has created all enhancements of man so far? That tension of the soul in unhappiness which cultivates its strength, its shudders face to face with great ruin, its inventiveness and courage in enduring, preserving, interpreting, and exploiting suffering, and whatever has been granted to it of profundity, secret, mask, spirit, cunning, greatness - was it not granted to it through suffering, through the discipline of great suffering?

What I know for sure is that there is no strength without challenge, adversity, resistance, and often pain.

All instincts that do not discharge themselves outwardly turn inward - this is what I call the internalization of man: thus it was that man first developed what was later called his soul.