Solitude.

The solitary is one who is aware of solitude in himself as a basic and inevitable human reality, not just as something which affects him as an isolated individual. Hence his solitude is the foundation of a deep, pure and gentle sympathy with all other men, whether or not they are capable of realizing the tragedy of their plight. More - it is the doorway by which he enters into the mystery of God, and brings others into that mystery by the power of his love and his humility.

- Thomas Merton