only to the extent which -- in chains, in dungeons,

... only to the extent which -- in chains, in dungeons, in hidden
corners, in the cells of philosophers, in the shops of traders --
some men continued to think, only to that extent was humanity able
to survive ... He was the man of extravagant energy -- and reckless
generosity -- who knew that stagnation was not man's fate, that
impotence is not his nature, that the ingenuity of his mind is his
noblest and most joyous power -- and in service to that love of
existence he was alone to feel, he went on working, working at any
price, working for his despoilers, for his jailers, for his torturers,
paying with his life for the privilege of saving theirs.
-- John Galt