No one writes sonnets about run defense. If they did, the imagery would toggle between the physical — there’s no more grueling aspect of a game than stuffing a run — and the psychological.

‘‘It’s still important,’’ Bears defensive coordinator Vic Fangio said. ‘‘Because most offenses in this league, if they can bludgeon you with the run, they will.’’

Once that happens, it’s over.

‘‘If you can’t stop the run, they’ll run on you all day,’’ defensive end Akiem Hicks said. ‘‘And it’s demeaning to a defense.’’

The inverse is true, too. The Bears’ defense has gained its psychological edge by dominating opposing rushing attacks all season.

With or without outside linebacker Khalil Mack, the Bears’ run-stuffing will be tested Sunday by the Bills, who figure to try to take the ball out of turnover-prone quarterback Nathan Peterman’s right hand.

‘‘You have to have an attitude,’’ inside linebacker Danny Trevathan said. ‘‘You have to be able to use it at the right time. It’s all about being aggressive but at the same time being smart. You don’t want anybody to run on you.’’

The Bears have one of the most dominant run defenses in franchise history. Consider:

• They’re the only NFL team not to allow a rushing touchdown this season. Only 15 teams in league history can make the same claim in the first eight weeks of any season. The last Bears unit to do so, in 1987, allowed a rushing touchdown in Week 9.

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• They’re allowing 83.1 rushing yards per game, the third-fewest in the NFL. Were the season to end today, it would rank as the fourth-best franchise mark since the 1970 AFL/NFL merger, behind teams in 2001 (82.1), 1985 (82.5) and 1988 (82.9). With five games left against teams ranked among the bottom 12 in rushing yards per game — the No. 21 Packers, No. 23 Bills, No. 29 Vikings twice and No. 31 Giants — the Bears have a chance to post the lowest average in modern franchise history.

• They have allowed only two players to surpass 100 rushing yards in a game in the last 25 games. The Dolphins’ Frank Gore needed overtime to do it last month, and Latavius Murray was stuck on 89 yards until gaining 22 before the Vikings took a knee to run out the clock in the finale last season.

Making historical comparisons is tricky, given the proliferation of the spread offense. In terms of yards per carry, the Bears’ 3.68 allowed is merely the 13th-best in modern franchise history. But the degree of difficulty has increased, Hicks said. Gone are defensive linemen such as Vince Wilfork, Tony Siragusa and Casey Hampton, behemoths who were used simply to combat the ground game.

As it is, teams are running less often against the Bears — and with little success. The Bears have allowed 10 rushes of 10 or more yards, the fewest in the league.

‘‘Sometimes there isn’t as much patience as there used to be around the league with [runs],’’ Fangio said. ‘‘But if you’re not doing well against the run, now you start playing stuff that makes the passes even better for them. . . . The value of the run has gone down a little bit just because of the way teams are playing. But if it’s not there, it will bother you.’’

Stopping the run enables Fangio to focus on the pass.

‘‘When you have a good feeling that you can [stop the run], it frees you up mentally,’’ he said. ‘‘Meaning me, as to what we can call.’’

A play-caller by trade, coach Matt Nagy knows the bind that leaves opposing offenses in.

‘‘To be good against the run — really good against the run — and force teams into throwing the ball, that’s an advantage for us,’’ he said.