 Charles Thomson, Secretary of the Continental Congress, discussing the proposed U.S. Seal, gave symbolic meanings for the colors in the seal, drawn from heraldry, with white signifying purity and innocence; red, hardiness and valor; and blue signifying vigilance, perseverance and justice.Over time, that explanation came to be associated with the flag.Over the years, other interpretations have included that red is for the blood of patriots, spilled in the fight to protect the country.