Nothing is worth reading that does not require an alert mind.

Warner’s remark treats reading as an active, demanding art rather than passive consumption. “Worth reading” is tied to the reader’s wakefulness: a valuable book should engage judgment, imagination, and attention, asking the mind to connect ideas, weigh claims, and notice nuance. The line also implies a standard for both writers and readers—writers should not merely entertain with easy effects, and readers should seek works that stretch them. In a broader cultural sense, it pushes back against superficial or purely diversionary print culture, suggesting that literature’s highest function is to sharpen consciousness and cultivate intellectual vitality.