The saying goes that a person can tell a lie so often he starts to believe it as truth. But what if a twinge of pain reminds him of his dishonesty with every step he takes?

We could all see Paul Pierce’s discomfort during Games 1 and 2. Doc Rivers admitted he had to alter his offensive play-calling to accommodate Pierce’s decreased mobility. Tony Battie, a former teammate of Pierce’s, said, “I know he’s hurt. … You can see it.” Elton Brand noted that he could also notice Pierce struggling, explaining, “When you’re hurting, it takes away some of your aggressiveness.” Rivers added in an interview on WEEI that Pierce’s knee wouldn’t get any worse by playing, but it wouldn’t heal either.

Pierce refused to acknowledge any limitations, repeatedly describing his knee as “fine.” But in the first quarter of Game 3, he utilized a spin move in the open court. He always moves methodically, but perhaps this was a step slower. The maneuver nonetheless freed him from the 76ers defense. He made it all the way to the rim, where he completely botched the layup. It was his sixth straight miss to begin the contest.

Pierce barely even jogged back on defense, watching as his teammates allowed a point-blank basket to Thaddeus Young. Chris Webber said, “Right there, you can tell something is wrong with his lift. (Pierce) got the spin, got wide open and couldn’t finish an easy layup.” On the ensuing possession Rajon Rondo sprinted coast-to-coast for a layup. Pierce could be seen dawdling at halfcourt. I wrote in my notes, “Missed layup was bad — lack of movement in transition was telling. Pierce is still hurt.”

So where did his next field goal attempt come from? What provided Pierce with the energy and power and explosiveness to burst past Andre Iguodala and finish an and-one dunk with Lavoy Allen fouling? And just 20 seconds later, how did Pierce muster the strength to do it again, this time spotting Allen coming on a double team, scooting away from the defending Jrue Holiday and slamming on the helping Thaddeus Young?

“Whether I shot the ball well or not, everything I was going to do was being with aggression,” explained Pierce.

Added Doc Rivers, “You could see early on, he missed layups, had no lift. And then all of a sudden he dunked the ball down the lane, he gets five offensive rebounds. I think guys like Paul and the Kobes, they have something in their minds that just make them who they are.”

Pierce scored 24 points, earned 14 free throws and grabbed 12 rebounds, better in each of those statistical categories than he could muster in Games 1 and 2 combined. He shot just 6 for 17 from the floor, but still managed to score efficiently because he was hell-bent on getting to the rim and drawing contact.

The Celtics were ornery after getting outplayed in both Games 1 and 2, and Pierce especially had motivation after those two wretched outings. It’s impossible to gauge how much Pierce’s two early dunks encouraged his Celtics teammates to match his aggressiveness, but those plays were certainly indications of an additional aggression — both for Pierce and for his team — that wasn’t present in the series’ first 96 minutes.

Afterward, Pierce again spoke of a healthy knee.

“I’ve felt good all series,” he said.

It’s either a calming truth or a misleading lie, and probably the latter. But as long as Pierce plays like he did yesterday, the veracity of his words doesn’t matter. The Celtics needed Pierce to attack, and he didn’t do anything but.