A book is a mirror: if an ape looks into it an apostle is unlikely to look out.

Georg Christoph Lichtenberg (1742–1799), a German physicist and satirist, is best known for his posthumously published notebooks (“Sudelbücher”), a running collection of aphorisms, observations, and barbed reflections on reading, learning, and human folly. The “book as a mirror” remark belongs to this tradition: it is not a speech or a set-piece essay line, but a notebook aphorism aimed at the moral psychology of reading. Lichtenberg wrote at a time when print culture and self-improvement literature were expanding, and he repeatedly mocked the idea that books automatically ennoble their readers. The line crystallizes his skeptical, Enlightenment-era view that character and intellect shape what one draws from texts.

Lichtenberg suggests that books do not magically transform readers; they reflect back the reader’s own capacities and dispositions. If a foolish or base-minded person (“an ape”) approaches a text, the result will not be wisdom or sanctity (“an apostle”). The metaphor of the mirror implies that reading is an active encounter: interpretation, attention, and moral seriousness determine what a book becomes in practice. The aphorism also satirizes naïve faith in education as mere exposure to great works. In Lichtenberg’s view, improvement requires a receptive mind and disciplined judgment; otherwise, even the best books can be misread, trivialized, or used to confirm one’s existing prejudices.

A book is like a mirror: if a monkey looks into it, you can’t expect an apostle to look out.
A book is a mirror; if an ass looks in, you can’t expect an apostle to look out.
A book is a mirror: if an ape looks in, no apostle will look out.