Venus Williams is 32 years old and has an autoimmune disease she first told us about at the 2011 U.S. Open, Sjogren's syndrome, that can leave her feeling lethargic even when she has rested and eaten well and treated her body as if it is a precious heirloom.
But the thing about precious heirlooms is that they can't just be taken off the shelf, dusted off and made new again.
So it is with Williams and her tennis game.
It is most likely that the Venus Williams we saw play tennis Monday at Wimbledon, the one who moved as if taking even one step was an effort, the one whose serve was more rudimentary than scary, the one who lost to 79th-ranked Elena Vesnina of Russia, 6-1, 6-3, is the Venus Williams we will mostly see now.
We can remember the Venus who won Wimbledon five times between 2000 and 2008 as one of the best female grass-court players ever.
We can remember how her long legs made her seem like a sprinter on the Wimbledon grass and how her long arms reached balls that seemed to be racing past her and smashed them back over the net, harder and faster.
But we probably won't see that Venus again.
Tennis fans might wish she would leave the game before there are too many more first-round bashings and before our memories are only of a worn-down, slowed-down, unremarkable player.
Williams, though, is unwilling to believe that she is the first-round loser we saw Monday. She seems to believe she is the five-time Wimbledon champion whose greatness was only occasionally trampled on by her younger sister Serena.
"I feel like I am a great player," Venus said after her loss Monday. "I am a great player. Unfortunately, I had to deal with circumstances that people don't normally have to deal with in this sport.
"But I can't be discouraged by that, so I'm up for challenges. I have great tennis in me. I just need the opportunity."
After disclosing her illness at the U.S. Open last year, Williams took nearly seven months off before returning to the WTA Tour in March at Miami. She was ranked 134th in the world and she knew she needed to greatly improve her ranking, to somewhere in the 50s, to have a chance at playing in her third Olympics, a goal Williams has not kept a secret.
She is ranked 58th now and expected to receive an Olympic invitation. She and Serena are playing doubles at Wimbledon, partly to prepare themselves, they hope, for a medal-winning shot at the Olympics, which will also be played at Wimbledon.
But it was suggested to Venus after her Monday loss that maybe all the effort she put into raising her ranking has been too much.
"Well, that's all I've fought for this whole year, so I hope that I can play well there," Williams said, referring to the Olympics. "For me it will just be an honor to be there and try to capitalize on that moment."
A testament to Venus' reputation came from Vesnina. "I think this is the biggest win in my career," she said. "To beat Venus in Wimbledon is just something amazing."
But maybe it is what Vesnina said next that is a testament to Venus' current form. "Actually, I really wanted to play against her because I have so much respect for both Serena and Venus," Vesnina said.
Wanting to play against the Williams sisters wasn't much in vogue until recently. But in the last month we've seen 30-year-old Serena lose in the first round of the French Open, a three-set battle to be sure and hardly a surrender, but still a stunning defeat to Frenchwoman Virginie Razzano. And now Venus is gone without much of a fight because she doesn't seem capable of summoning one.
The era of Williams sister domination seems over. Even if Venus doesn't see it yet.