In cases where two actions combine to cause an escape, upon whom does liability rest?

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When two contributing factors meet, liability does not attach to the preceding, non-compelling cause. This is established by analogy to a case where one digs a well, and another person's slave throws himself into it; the liability is not attached to the digger. Liability remains with the immediate cause, as in the case where the creature is actively driven away or escapes immediately after the release. The direct action of the opener is considered ineffective if an external, immediate driver is involved, similar to when a bird is startled, or a dog is set upon someone, or fire is set in someone's property; the effect of the fire is nullified when the judgment cannot be ascribed to it.