These decorations serve no functional purpose for timekeeping accuracy; their purpose is purely artistic. They are the hidden poetry of the watch, a testament to the craftsman's pride, meant to be admired by the owner through a sapphire crystal case back. It is beauty for beauty's sake, a private luxury known only to the wearer.
If the basic timekeeping function is the prose of watchmaking, then complications are its poetry. A "complication" is any function in a watch beyond the simple display of hours, minutes, and seconds. They represent the pinnacle of mechanical artistry, pushing the boundaries of what is possible within a confined space.