For I say unto you in all sadness of conviction that to think great thoughts you must be heroes as well as idealists. Only when you have worked alone -- when you have felt around you are a black gulf of solitude more isolating than that which surrounds the dying man, and in hope and despair have trusted to your own unshaken will -- then only can you gain the secret isolated joy of the thinker, who knows that a hundred years after he is dead and forgotten men who have never heard of him will be moving to the measure of his thought -- the subtle rapture of postponed power, which the world knows not because it has no external trappings, but which to his prophetic vision is more real than that which commands an army. And if this joy should not be yours, still it is only thus you can know that you have done what lay in you to do -- can say that you have lived, and be ready for the end.
Oliver Wendell Holmes