Guarded by thousands like I was gold, And I can never go old, What am I?

Defeat runs through me, shattered ranks undone. Extend the ruin, find the path they've won. But whole, I carve the channel, cut the groove, I send you on your way, yet never move.

Without a bridle, or a saddle, across a thing I ride a-straddle. And those I ride, by help of me, though almost blind, are made to see. What am I?

In my bosom a drum does play, a rhythm that guides the night and day. Oh, my dear, it's quite the feat, the steady pace of life's own beat.

Tell me now, and don't be late. What kind of bird can lift the most weight?