Carter, Twentieth Century Type Designers, (p.9):

Offending readers with distortions of the basic proportions of letters, or even attracting their notice with minor eccentricities of detail, creates a resistance not only to the type but to the message of which the type should be the faithful messenger.

Carter on well-designed type (p.187):

Finally, we should always remember that well-designed type is only the first step towards readable texts and handsome pages: bad setting and thoughtless layout can ruin the best-looking typeface. I hope that this account of the labours of some of the creators of type will increase the respect among users and consumers for these small miracles of art and skill.

Morison, First principles of typography (1930):

Type design moves at the pace of the most conservative reader. The good type designer therefore realises that, for a new fount to be successful, it has to be so good that only very few recognise its novelty. If readers do not notice the consummate reticence and rare discipline of a new type, it is probably a good letter. But if my friends think that the tail of my lower-case r or the lip of my lower-case e is rather jolly, you may know that the fount would have been better had neither been made.

Tracy, The Typographic Scene, (p.11):

Typography is a professional activity directed towards a practical, and usually commercial, result.

Tracy defends Tschichold (p.56):

But it was unreasonable to criticise Tschichold as though the new typography had the status of religious doctrine and he had defected from it. He had turned away from the style, not against it.

Tracy on the role of typographer (p.60):

Since most typographic work is done in the hope that it will be read (though there is never any guarantee of that) it is not very sensible of the designer to adopt practices that may repel a potential reader.

The competent typographer serves the one by securing the attention of the other. The really good typographer does something more: he invests his work with such visual quality as to persuade us that (whether or not it is true) the words he is presenting to us are going to be a pleasure to read.

Rogers, Paragraphs on Printing, (p.57):

Uneven leading or extra leading between paragraphs may sometimes be necessary in a reference or other special kind of book, but for ordinary text it throws lines out of register, interrupts the continuity of the text, and offends the eye.

Robert Bringhurst:

Typography history is just that: the study of the relationships between type designs and the rest of human activity—politics, philosophy, the arts, and the history of ideas. It is a lifelong pursuit, but one that is informative and rewarding from the beginning. (p. 112)

Always discovering something interesting with every reread of The Elements of Typographic Style.

James Felici, The Complete Manual of Typography, on digital typesetting (p.5):

Like handset type, digital type must also take into account spaces within and between lines, such as paragraph indents or extra space between a headline and a text below it. Although those area appear blank on the printed page, it’s important to think of them as filled with space rather than as simple voids.

If there is an essential truism in typesetting, it is that a page contains no voids, only spaces between printed elements. The essence of typesetting is regulating the size of those spaces to control the balance and rhythm between black and white. This is the key to a graphically harmonious page—one with good type color—as well as to text that is pleasing and easy to read.

Felici on controlling space (p.21):

Typesetting is a game of controlling spaces, so its tools are all keyed to precise measuring.

Felici on font versus typeface (p.29):

The font is the cookie cutter, and the typeface is the cookie.

In the introduction of Typefaces for Books, James Sutton and Alan Bartram argue:

While display faces can be extrovert, colourful and rich in character, book faces must be transparent, allowing the reader to hear the author’s voice without distortion or interference.

It is in answering this little question of the author’s voice that the book typographer’s task lies. He must invent an action, a tone, and decide on the volume: should he whisper or shout or sing? whatever he decides he must keep in mind that he is making a window through which the reader can see the view as clearly as possible and be quite unconscious of the proportions of the glazing bars.

In Shaping Text, Jan Middendorp writes:

A good jazz musician will master different styles and genres in order to feel in control in various formations or in jam sessions. A professional graphic designer, too, will have to improvise and find ways of communicating all kinds of contents in all kinds of circumstances.

In Design Elements: Typography Fundamentals, Cullen writes:

Type for the web, as well as digital devices and gestural interfaces, meet challenges because conditions vary, unlike fixed mediums such as print. Multiple browsers, platforms, and screen sizes present type differently. Typefaces suited to one might not suit another. Expect the unexpected in digital realms. Be flexible and responsive. Digital formats know no bounds. Unlimited virtual space offers potential unseen in other areas.

In the introduction of Designing Type, author Karen Cheng writes:

Type is the visual manifestation of language. It is instrumental in turning characters into words, and words into messages. In music, the quality of an individual singer can completely change the experience of a composition. In communication, type is the visual equivalent of an audible voice – a tangible link between writer and reader.