Six in the third place means

Undeserved misfortune.

The cow that was tethered by someone

Is the wanderer's gain, the citizen's loss.

Sometimes undeserved misfortune befalls a man at the hands of another, as for instance when someone passes by and takes a tethered cow along with him. His gain is the owner's loss. In all transactions, no matter how innocent, we must accommodate ourselves to the demands of the time, otherwise unexpected misfortune overtakes us.