Rubric: “Fantasia on a Pleni. lower the fourth fret a little towards the rosette. Mode 1, second level [of difficulty]”. In the table of contents Valderrábano adds that the Pleni, that is from the “pleni sunt caeli” section of the Sanctus is from a mass by [Noel] Bauldoin (=Baldeweyn). To date, this work has not been identified. The fantasia is a short work of 86 compases, largely through composed and non-imitative, apart from one brief section. The instruction to adjust the fourth fret is difficult to interpret. If the vihuela were in equal temperament, this would make leading tones b-natural (III/4), f# (IV/4), c# (V/4) and g#’ (I/4) sharper as occurs using Pythagorean temperament. If Valderrábano’s norm were more like mean-tone temperament, it would make these notes sound almost as if the were in equal temperament.

The work begins with melody in the tenor = Theme 1. Theme 2, however is more important: it begins at c. 3, and is 8 compases long. After this melody, Valderrábano uses free polyphony to c. 25. At c.26, theme 2 is given again in B, then follows a second section formed from the use of a falling 3rd as the central idea of theme 3, treated in imitation. Cadences in motion prolong this section to c. 61. Theme 4 makes several appearance as a motive in all voices in this somewhat imitative passage > c. 79 – 86 free.