Correct spelling, indeed, is one of the arts that are far more esteemed by schoolma’ams than by practical men, neck-deep in the heat and agony of the world.

Mencken is mocking the disproportionate reverence for “correct spelling” in formal schooling compared with the priorities of people engaged in the rough work of life. By contrasting “schoolma’ams” with “practical men, neck-deep in the heat and agony of the world,” he frames orthographic correctness as a social shibboleth—an academic or genteel marker of respectability—rather than a tool that necessarily improves judgment, competence, or effectiveness. The line fits Mencken’s broader satirical stance toward American moralism and pedantry: he suggests that institutions often elevate tidy, measurable rules (like spelling) while undervaluing the messy, consequential skills demanded by real experience.