...in their millenial and long-lived patience they knew...

...in their millenial and long-lived patience they knew quite well how, in a hundred years, or a thousand years' time, or else, perhaps, tomorrow, in an hour's time, for it was all a gamble, a million to one chance, but all the same there was a chance that if they kept on shaking their chains, one day, some day, the clasps upon the shackles would part.