This is Kannon who ranges over the ocean of life and death, symbolizing great power of briskness and effort to conquer Four Hindrances, as if the treasure horse of Tenrinjoo (universal ruler) ranges over all around to conquer, and it is said it eats up the heavy hindrance of avidya just like a gluttonous horse.
転輪聖王の宝馬が四方に馳駆して、これを威伏するが如く、生死の大海を跋渉して四魔を催伏する大威勢力・大精進力を表す観音であり、無明の重き障りをまさに大食の馬の如く食らい尽くすという。