Donald Knuth: "Probably the most beautiful spacing ever achieved in any typeset book appeared in 'The Art of Spacing' by Samuel A. Bartels (1926). This book was hand set by the author, and it contains about 50 characters per line. There are no loose lines, and no hyphenated words; the final line of each paragraph always fills at least 65% of the column width, yet ends at least one em from the right margin. Bartels must have changed his original wording many times in order to make this happen; the author as compositor is clearly able to enhance the appearance of a book."