What did Tallis and Byrd mean to convey by their use of the word "argument" in their title, Cantiones, quae ab argumento sacrae vocantur?

Thomas Tallis's and William Byrd's Cantiones, quae ab argumento sacrae vocantur (songs, which by their argument are called sacred) of 1575 is one of the first sets of sacred music printed in England. It is widely recognized as a landmark achievement in English music history. Dedicated to Queen Elizabeth I to mark the seventeenth year of her reign, each composer contributed seventeen motets to the collection, which proved to be greatly influential among the era's composers.

But what did Tallis and Byrd mean to convey by their use of the word "argument" in their title? The current view is that they treated their project as an opportunity to pull together a grand compendium of musical accomplishment that drew on the past, but looked to the future, and that the texts functioned as mere vehicles for musical display. In contrast, this book claims that these very texts were chosen by the composers to develop a theme, or argument, on the topic of sacred judgment. In offering a new interpretation of the song collection Smith employs a carefully constructed musical, literary, theological, and political argumentation. The book will encourage new ways of approaching and interpreting Tudor and Elizabethan sacred music.