Why is the trim or decoration of a man's hat always on the left side?
In the seventeenth century, the swaggering Cavalier hat was conspicuous with broad brim either rolled or cocked and ornamented with long ostrich feathers, "weeping plumes." The crown was often encircled with a jeweled necklace or a silk band sewn with gems. A large gold ornament held the plumes.
In those days of free sword play, the feathers were placed to the back or left side of the hat, permitting freedom of the sword arm. In addition, the hat ornament was often a love token, and the position on the left side signified the heart or love. The decoration has ever since remained on the left side.