* Ballet chief leaves hospital, to have treatment in Germany
* Recounts agony after attack, says knows who was behind it
* Attack has tarnished image of Russia's Bolshoi Theatre (Adds details, background, quotes)
By Anastasia Gorelova and Thomas Grove
MOSCOW, Feb 4 (Reuters) - The Bolshoi Ballet's artistic director left hospital on Monday saying he knew in his heart who was behind the acid attack that threatens his sight and the reputation of one of the world's great theatres.
Sergei Filin, his face scarred and eyes hidden by dark glasses, hinted last month's attack was linked to his work in the fiercely competitive world of ballet. He said his attacker had looked at him from behind a mask "with fear in his eyes".
"I fell on my face in the snow and began to rub snow in my face and eyes," he said in an interview with Rossiya 24 television before his discharge.
"I was in terrible, unbearable pain."
He said he lay in the empty street in front of his apartment building for 20 minutes after the Jan. 17 attack pressing his face into the snow, until he caught the attention of a security guard who called an ambulance.
Dressed in black, he spoke only briefly to reporters before stepping into an ambulance, his wife Maria clutching his arm. He was due later on Monday to fly to a German clinic, widely reported to be in Aachen.
Filin said the attack was the culmination of weeks of threats and was meant to end his career as one of the more influential artists at the Bolshoi Ballet, an enduring symbol of Russian culture since the era of Catherine the Great.
Filin said his sight, invaluable for the grandiose and carefully scrutinised productions of the Bolshoi Ballet, could be better but that he could still see "fuzzy" objects.
Asked if he knew who had ordered the attack, he said in the television interview: "Every person has an organ called a heart, and my heart knows who did it, and in my soul I have an answer to that question."
"I have forgiven each and everyone who participated in the act," he said.
He wore a netted bandage that covered his scalp and neck but revealed a slightly scarred and blotchy face.
"I feel well, I'd even say great, if only my eyes could see a bit better," Filin, 42, told reporters outside the hospital
Rivalries in the theatre have often in the past led to personal battles between artists and have contributed to the ballet going through five artistic directors since 1995.
Filin has already had five operations in Moscow, and Russia's top ophthalmologist Vladimir Neroyev told Interfax news agency that rehabilitation of Filin's eyesight could take months and may involve more operations in Germany.
Filin said he had been in almost daily contact with acting artistic director Galina Stepanenko, who has taken over his role temporarily.
"Galina is wonderful. The theatre is in good hands," he told reporters.
He dismissed theories that his attack was connected with the sale of tickets, often scalped and resold at sometimes exorbitant prices.
Investigators have questioned Filin and others at the ballet, and Filin said that he will continue to be in contact investigators during his time in Germany. (Reporting by Anastasia Gorelova, writing by Thomas Grove, Editing by Timothy Heritage)