A square wave is a waveform consisting of instantaneous transitions between two levels. Fans of Fourier analyses argue a square wave can be made by summing a fundamental with an infinite series of odd-multiple frequency sine waves at diminishing amplitude, while audio engineers suggest familiarity with the tonality of a square wave helps identify symptoms of distortion, given the extent to which clipping squares a waveform.
Visually speaking, the squared off duty cycle of a square wave suggests both balance and maximised utility, based on equal oscillation between full expression in an upwards or positive direction, and an equally full expression in a downwards or negative direction. Experientially speaking, the rapid and repetitive cycle between full exertion and deep rest can similarly distort perspectives and bring out the higher harmonics. In life as in music, there is both magic and mayhem in going repeatedly back and forth at full blast.