In classifying primary musical documents from the fifteenth and sixteenth centuries, we are dependent upon a variety of techniques of music-historical research – analysis of watermarks, repertory, concordances, the cultural and historical contexts – which furnish the means for evaluating the authority of the sources, ‘the degree of presumptive similarity to the lost … autograph’. One of the principal points in attempting to establish the credentials of the primary sources for the Josquin motets is that they contain alternative readings that condition our perception of the pieces. The choice of readings will inevitably depend on our ability to identify those sources that preserve more authoritative redactions for a given work. A number of techniques are ordinarily used for assessing these sources: (1) that a source is taken prima facie as representing the best tradition that we can discern is an assumption based on its time and place of origin; (2) details of filiation as documented in the variants themselves can suggest lines of transmission and the relative plausibility of sets of readings; and (3) some sources may assume greater importance because they preserve redactions that conform to convictions about Josquin's style. While each of these techniques has something to recommend it, the last assumes considerably more refined criteria than we now possess for describing Josquin's compositional practices, and a considerably broader and deeper knowledge of his whole oeuvre than most of us possess. For, as has been pointed out, ‘the textual critic must often choose, on the basis of his knowledge of such things as the style of the author or the scribal practices of the period, those variants upon which he wishes to base his stemma. Classical philologists have centuries of experience and a multitude of examples to draw upon when confronted with choices between anomalous readings; music historians have no such storehouse of knowledge.‘ Since many of the variant readings in question are equally plausible, very often the choices are not between versions that are manifestly erroneous, on the one hand, and those that are not, on the other, but between equally acceptable versions, each of which is musically permissible. The first two of the techniques referred to above afford a more systematic and objective means at this time for ranking the primary source material, and a basis on which to advance tentative hypotheses of plausible content that suggest ways of determining what an authoritative version of a piece would look like.