E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Horse and his Rider.
One of Æsops fables, to show that nations crave the assistance of others when they are aggrieved, but become the tools or slaves of those who rendered them assistance. Thus the Celtic Britons asked aid of the Saxons, and the Danish Duchies of the Germans, but in both cases the rider made the horse a mere tool.