Can Tahir change his spots?
What is it they say about leopards? They cannot change their spots, right? Wrong.
Four years ago, it was discovered, Rudyard Kipling was onto something when he wrote his tale of how the leopard got its spots. It was described as a gift from an Ethiopian, who said, "Now you can lie out on a leafy branch and look like sunshine sifting through the leaves; and you can lie right across the centre of a path and look like nothing in particular." The leopard was being prepped for camouflage, which implicitly implies change. It has taken the better part of a hundred years but scientists now agree coat-marking helps animals blend into their surroundings, and even changes over time to better adapt. Leopards that live in dense bush will have more intricate and complex spots than those that migrate to grasslands, where future generations adapt to fit the less-is-more theory.
Once heralded as an attacking addition to the Test pack, Tahir's lack of wickets in Galle has led to questions over his role. His lone strike in 45 overs would cause further raised eyebrows considering Galle welcomes his kind with open arms, especially in the latter stages of a Test.
Although the turn was described as being slower than normal, Sri Lanka's two spinners shared 11 victims between them. Tahir, who bowled on the fourth and fifth days, could not be a similar threat. Given that he is South Africa's premier spinner, he should offer more in the twilight stage of a Test, especially in one where conditions suit him.
Henderson wants to put paid to all that. "He must not fall into the trap that, because we are in Sri Lanka, wickets are dry and the spinners come into play, he feels he must take five wickets. It's about building the pressure. Wickets are a bonus," Henderson said after the Galle Test.
If you are searching the memory bank for where you have heard sentiment similar to that before, it is what South Africa used to say when they spoke about Robin Peterson, Paul Harris, Nicky Boje and Henderson himself.
"We always talk about spinners trying to be consistent in the areas that they bowl, that doesn't mean how many runs they go for but how many singles they go for in an over," Henderson said, about what is expected of Tahir now.
He thought Tahir showed improvement on the fifth day, that "he was more consistent," and "that's what coaches want their bowlers to do." On day four Tahir bowled 11 overs for 41 runs and his variation was the googly-turned-long hop. On day five he bowled nine overs for 24 runs and he used the googly better. There was a difference, albeit not a threatening one, but Henderson didn't mind that.
"On day four there were too many inconsistent deliveries within overs, which didn't create enough pressure," Henderson said. "My message will always be to the spinners, yes we have to spin the ball but can we create pressure? Can we be consistent in our areas? Immi knows what works for him. He has got his way of thinking and practicing to get it right so I'm quite happy with the way he bowled on day five.
"We talk about partnerships in batting and we also talk about partnerships in bowling. If your spinner is going at sixes one end, Steyn will struggle and we saw that this morning. If you don't strike it's not a problem, but let's hit our areas consistently and I thought he hit them really well today."
That is Tahir's homework for Colombo, rather than improving his strike rate. "The challenge in the longer format for us is not to put that pressure on yourself," Henderson said. "In one-day cricket you've got four guys on the boundary, in Test cricket there is none but the secret is just to try and build pressure.
"It's to ask yourself: how many dot balls can I bowl as a legspinner? How many dot balls can I bowl when I bowl my googly? How many dot balls can I bowl when I change my angle on the crease? I think that's the recipe for us. I don't think Imran feels the pressure of, 'I have to take wickets'. It's just a way of thinking of what his role is and sometimes spinners fall in the trap and think they have to be the strike bowler, when what makes us consistent is stopping the game."
All that means is Tahir is no longer seen as a strike bowler because South Africa have realised their seamers can do that job just about anywhere. With Dale Steyn and Morne Morkel taking 16 wickets in Galle, there is little argument against that belief, but it also means Tahir will be asked to change his mindset.
Tahir is a naturally attacking bowler. He has described himself that way on many occasions and even said he does not mind being hit around a bit in order to take wickets. South Africa had been moving away from using their spinners in defensive roles, which suited Tahir, but everything Henderson said indicates they are on their way back there. Tahir has also been open to change, willing to try to develop other skills such as fielding, batting and holding up an end, and he has been successful in all three. Whether he can do any of them as a primary function is doubtful.
What that means for JP Duminy is that he may be asked to bowl more. What that means for Dane Piedt - the reserve spinner on tour, who topped the first-class wicket charts last summer but has an impressive economy rate - will only be known in the future.
But what it means for Tahir is that unless he changes his spots, he may find his Test career fading sooner than he would have liked.
Firdose Moonda is ESPNcricinfo's South Africa correspondent