E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The Gold and Silver Shield. Two knights coming from different directions stopped in sight of a trophy shield, one side of which was gold and the other silver. Like the disputants about the colour of the chameleon, the knights disputed about the metal of the shield, and from words they proceeded to blows. Luckily a third knight came up at this juncture, to whom the point of dispute was referred, and the disputants were informed that the shield was silver on one side and gold on the other. This story is from Beaumonts Moralities. It was reprinted in a collection of Useful and Entertaining Passages in Prose, 1826.
The other side of the shield. The other side of the question. The reference is to the Gold and Silver Shield. (See above.)
That depends on which side of the shield you look at. That depends on the standpoint of the speaker. (See above.)