Steam does not have the same reputation as fire but it can be just as dangerous. Unlike flames, which are audible in their crackling and visible in their vibrancy, gas is invisible. You can't fully sense the threat it poses until you feel it and then it really hurts. That's what Dale Steyn was like today.
He had gone 67 overs before today without a wicket, so even though the opposition could see and hear him and knew he could do damage, they may not have known when or how much. Given that it was the longest amount of time in his nine-year international career that Steyn had not had success, he was silently seething. The only way for him to cool down was to come out firing.
What was important was the way Steyn started in conditions that offered a little more to the bowlers because of the morning drizzle. "Because the pitch was covered, there was a little bit of a sweatiness that happened. For the first hour and 20 minutes, there was a little bit in the wicket," Steyn said. "A lot of the balls were misbehaving."
There was also a different approach from Steyn. He bowled fuller first up and induced edges off both M Vijay and Cheteshwar Pujara's bats in his first two overs. The edges evaded the fielders, which would ordinarily irritate Steyn, but didn't this time because it showed him he was not was far from ending his drought.
Like steam, he kept rising. By peppering the batsmen with well-directed short balls and mixing them up with full ones, Steyn knew he could produce a wicket. By his third over, having found reverse-swing as well, India felt the suffocation starting. Pujara pushed uncertainly and AB de Villiers took the catch.
Immediately, South Africa lifted too. There was whooping, jumping and high-fiving in joy at having finally broken through. But there was also a sense that something had sparked.
In the next 10 balls, there was confirmation of that. Steyn removed Vijay and Rohit Sharma off successive deliveries. The first went fending a short ball and was caught down the leg side, the second left one that swung into him. Steyn confirmed it was Vijay's scalp that lit him up. "Sometimes if you can get a soft dismissal, you can get on a roll. You need that momentum shift. I was lucky enough to get that soft one down the leg side," he said.
Steyn's first spell of the day read: 5-2-19-3. The three wickets came in 10 balls. India went from 198 for 1 to 199 for 4.
With Steyn threatening to decimate India's advantage further, Graeme Smith could have kept him on for longer but knew it would be better to save him for the second new ball because the pitch was becoming better to bat on. Steyn only returned when it became available and then he used it to attack.
As the first over of his second spell came to an end, Steyn struck Ajinkya Rahane's helmet with a bouncer. Rahane was not watching the ball and ducked into it. Nothing broke and there was no blood, but butterflies would have fluttered in stomachs. Rahane quietened them with a pull in the next over and a drive in the over after that, but the barrage did not let up. Steyn hit Rahane again when the batsman did not duck in time and was caught on the arm.
Credit must go to Rahane for not being so rattled by the scare tactics that he gave it away. He walked off the pain, refocused and in the end scored his maiden Test fifty. Virat Kohli also saw off the wave of aggression from Steyn's second spell. That read: 4-0-19-0. India were unscathed in that period.
Steyn could have come back as soon as the teams returned after tea but Smith chose to use Morne Morkel and Robin Peterson. Steyn was only given the ball when neither managed to break through - particularly not Peterson, whose continual leakage will leave South Africa with serious concerns about their spin department.
Steyn beat MS Dhoni and then dismissed him chasing a wide one. In almost a replica of his first spell, Steyn's next two wickets came in the space of four balls. Zaheer Khan backed away from a short one and slashed behind and then Ishant Sharma offered a regulation caught behind.
Steyn's third spell read: 5-1-13-3. Three wickets came in eight balls. With JP Duminy also among the scalps and Morkel taking the last wicket, India went from 320 for 5 to 334 all out.
Their collapse was triggered by Steyn, who was ablaze from the first ball he bowled to the last. In the process, he claimed his 22nd five-for, which he regarded as "one of my better ones because I had gone so long without taking a wicket". On previous occasions - and there have been very few of them - when Steyn has struggled he has resorted to showing his testiness. This time it was the complete opposite.
He allowed his satisfaction to shine through. "I am actually really proud of myself because most people would capitulate and not be able to come back from that dry spell," he said. Most people are also not able to act as the flammable Steyn is. When he ignites, he takes the team with him. That was on show today. South Africa's stubbing out of the Indian tail featured five wickets for just 14 runs. Then the opening pair began the reply by scoring at more than four runs an over to show South Africa's intent to seal the series. If they do, they will have Steyn to thank for lighting the first flare.