At a printers’ convention in August 1892, De Vinne proposed the ideal of “masculine printing,” in opposition to the “feminine” variety that he saw as a weakening of standards. This latter was an approach interested in ornamental effects and especially in a cultivation of hair-line delicacy…By contrast: “The object of the masculine style [was] the instruction of the reader.”

Kinross, Modern Typography, page 53

Disregard the unnecessarily gendered language and you’ll find a strong argument for legibility. And by legibility, I mean not merely what’s required to discern the words on a page, but a design that encourages thoughtful reading. De Vinne’s use of the phrase “instruction of the reader” suggests a concept of design that is oriented towards learning.