Have not I myself known five hundred living soldiers sabred into crows' meat for a piece of glazed cotton, which they call their flag; which had you sold it at any market-cross, would not have brought above three groschen?

Carlyle is stressing the gulf between material worth and symbolic value. A flag, as mere “glazed cotton,” is nearly worthless in a marketplace; yet in war it becomes a concentrated emblem of collective identity, loyalty, and meaning—powerful enough that men will die to defend it. The grisly image (“sabred into crows’ meat”) underscores how human beings routinely sacrifice life for abstractions (nation, honor, cause) that cannot be priced. The line also carries Carlyle’s characteristic skepticism toward purely economic measures of value: what matters most in human life is often precisely what cannot be reduced to cash equivalence.