Billings wrote long prefaces to his works in which he explained (often in an eccentric prose style) the rudiments of music and how his work should be performed. His writings reflect his extensive experience as a singing master. They also provide information on choral performance practice in Billings's day; for instance, a passage from the preface to The Continental Harmony indicates that Billings liked to have both men and women sing the treble (top) and tenor lines, an octave apart:
... in general they are best sung together, viz. if a man sings it as a Medius, and a woman as a Treble, it is in effect as two parts; so likewise, if a man sing a Tenor with a masculine and woman with a feminine voice, the Tenor is as full as two parts, and a tune so sung (although it has but four parts) is in effect the same as six. Such a conjunction of masculine and feminine voices is beyond expression, sweet and ravishing, and is esteemed by all good judges to be vastly preferable to any instrument whatever, framed by human invention.[6]