Looking at Fishing Lines From the time when anglers began to appreciate catching fish as a sport, and not only as a skill used to harvest food, the earliest fishing lines were reported to be made of horsehair and gut, later giving way to silk—the era was the seventeenth and eighteenth centuries. These silk lines were cast with a whippy pole or rod, the precursor to a fly rod. Later, silk bait-casting lines became popular. The leader on the horsehair or silk line was gut, a material which was less obvious to fish when underwater and therefore less of a threat to fish than the heavier silk casting line to which it was attached. The leader was the transitional piece of the connection intended to be as translucent as possible so the fish might be fooled into eating the fly or bait. This principle of using a line less visible or at least less noticeable to fish paved the way for the nearly invisible lines such as today's monofilament (a single strand of extruded nylon, he...