The inverse-distance dependency of the Biot-Savart force law between current-conducting filaments leads – curiously – to pairing of filaments. This shows 3 filaments where only two will interact strongly while the third remains quiescent. This leads directly to “twoness” or :doubleness when many filaments are present in a plasma with a significant magnetic field. Credit: adapted from Fig. 3.21, Physics of the Plasma Universe, Peratt, Springer Verlag,1992