The Information Density of Old Textbooks

There&rsquo;s a YouTube short making the rounds about how textbooks seem to have been dumbed down: The upshot of the video seems to be that the venerated classic textbooks of yesteryear — e.g. Thomas&rsquo; Calculus and Analytic Geometry; 2nd ed. (~1958) — got to their essential material (e.g. the derivative) much more directly than do the bloated, ridiculously-expensive textbooks of the present…