The inertia hardest to overcome is that of perfectly good seconds.

Fischer’s aphorism plays on the physics term “inertia” to describe a common human resistance to change: not the pull of obviously bad habits, but the comfort of “perfectly good” ones. “Seconds” suggests second choices, second-best arrangements, or the habit of settling for what is adequate. The line implies that mediocrity can be more adhesive than failure because it provides plausible reasons to stay put—things are fine, so why risk disruption? In that sense, the quote is a critique of complacency and a call to pursue excellence or growth even when one’s current situation is respectable.