Whereas external evidence can often be obtained without looking beyond the title-page, the pursuit of internal evidence requires close attention to every word and phrase. However, it also requires some degree of reference to information outside the work, for, as David Lake has pointed out, ‘without some unquestioned attributions no other attributions can be questioned’. By an extension of this observation, evidence from, say, the opinions expressed in a work only becomes operative when there is an author or authors who might have held these opinions. If internal evidence exists in a pure form it can only be in those cases when the common authorship is established of two anonymous works. Arthur Sherbo divided up internal evidence between style and ideas, with style also embracing ‘range and density of learning and allusions, and parallels of various kinds with known works by the particular writer in question’. Style in the narrower sense will be considered in Chapters six and eight; this chapter will concern itself with the other elements instanced by Sherbo, along with decorum and aesthetic preference.

When Sherbo delivered his paper in 1958 there was still something suspect about the claim that questions of attribution could be determined by internal evidence alone.