I. READABILITY

What does it mean for a text to be “readable”? In English some have made a distinction between legibility and readability: 

“Legibility” is based on the ease with which one letter can be told from the other. “Readability” is the ease with which the eye can absorb the message and move along the line.”—Types of Typefaces (1967) p. 84-5.

The same distinction is discussed by Walter Tracy:

[Readability] describes the quality of visual comfort—an important requirement in the comprehension of long stretches of text, but, paradoxically, not so important in such things as telephone directories or air-line timetables, where the reader … is searching for a single item of information [and where legibility is most important].
—Letters of Credit (1986), p. 31. 

My main goal in my revival was maximizing this quality of “visual comfort.”

What qualities of a typeface make for visual comfort? Here there is no consensus but raging debate, including even over whether the concept is valid. I will not go into the debate here, but just relate my own ideas on reading comfort that I have in effect tested in creating my revival. (For the debate see the survey paper by reading psychologist Kevin Larson, and this Typophile thread.