Riddle Poem-5

Riddle poem-5 - - - - - - - - - - - - I can run but never walk I have a mouth but never talk I have a head but never weep I have a bed but never sleep Yet never do I feel tired Life to me is sweet, green and gold I pass through meadows Happy to see cool cows And leaves falling green and brown Upon my breast and crown While through woodland I come across rocks that impede Swiftness of my speed Though never do I mind Day in and day out Racing and racing without Stopping a little to attain Nirvana By merging with that wide, eternal place of heaven Now can you tell who I am? Sometimes wild and sometimes calm