From William Hazlitt's essay *On the Ignorance of the Learned* (1821). Select the word that fits the blank. "He clings to [his book] for his intellectual support; and his dread of being left to himself is like the ______ of a vacuum."

The simile compares the learned reader's *dread* of being left alone with his own mind to a classical principle from Aristotelian physics — *horror vacui*, "nature abhors a vacuum." The phrase *the horror of a vacuum* was a stock allusion in nineteenth-century English prose for any deeply rooted aversion. Hazlitt is making the learned man's discomfort feel as primal and physical as nature's supposed revulsion at empty space. - "Love" reverses the simile. - "Indifference" is the absence of feeling — Hazlitt's word *dread* requires a strong feeling. - "Mystery" doesn't fit; the point is not that vacuums are puzzling but that they are repugnant.