Of all failures, to fail in a witticism is the worst, and the mishap is the more calamitous in a drawn-out and detailed one.

Landor’s remark treats wit as a high-risk social art: most failures can be excused, but a joke that falls flat exposes the speaker’s judgment, timing, and self-awareness all at once. The second clause sharpens the point—an overlong, elaborately set-up witticism magnifies embarrassment because it demands sustained attention and raises expectations before collapsing. Implicitly, the line advocates brevity and restraint in conversation and writing: if wit is attempted, it should be economical, and one should avoid the vanity of “explaining” or laboring a joke. The observation also reflects a broader literary ideal of concision, where excess detail can turn intended brilliance into tedium.