信马由缰

Explanation: Letter by let. Wandering aimlessly on horseback. Metaphor of a way. Also be used to non-assertive, with the external force transfer. 　　Usage: Partial official; as predicate; analogy wandering 　　Source: Qing Li, Green Park "Qiludeng" said the eighty-sixth back to the mother of Wang is a dizzy, Shao-Wen is a Xinmayoujiang son. " 　　Examples: He walked to Central Park ~, unwittingly bought a ticket inside. (Lao She, "Zhang's philosophy" the thirty-second chapter) Thesaurus:  ride withlax reins