A quotation in a speech, article or book is like a rifle in the hands of an infantryman. It speaks with authority.

Behan likens quotation to a weapon: once you invoke an established authority—scripture, a classic, a statesman, a poet—you borrow its force and credibility. In rhetoric, a well-chosen citation can do what mere assertion cannot: it “speaks” as if backed by a larger tradition, making the speaker seem disciplined, informed, and aligned with recognized truth. The simile also carries an ironic edge typical of Behan: authority can be deployed tactically, even aggressively, and quotations can function less as illumination than as ammunition. The line thus comments on how cultural capital and inherited prestige shape persuasion in public speech and writing.