Corrections in red.  Stylistics in blue.

A Fire And Combustion

Our today's talk [1] will be about fire and combustion. You can ask me: "Wait, wait, but those things are the same, aren't they?" Yes, of course, those things are very close [similar] to each other. But they aren't the same [they aren't identical]. Fire is [better: has been] known to people since extreme antiquity. But even in antiquity people knew the power of fire. (A) fire was extremely important for ancient people. It gave light, warmth, and, one of its most important features, the safety. Wild animals were afraid of fire and travelled by side of human's fires. ?? [I think you mean, "avoided human fires"]. People believed in the power of fire and used it everywhere. Later they learned to use fire more effectively - they started to use stoves and other devices, which made a combustion more efficient. But it was not a knowledge about combustion, just some observations. It continued, until people got to know about how the fire "works". It gave a push towards the invention of internal combustion engines. At first time, it was huge machines, but, with the passing of time, they became more and more efficient. And now, at the present day, we can't even think about the world without engines. Engines give power to people power. They give to people a freedom of movement, and they provide to people comfort and pleasure. But the mankind was not stopped at this stage of evolution. The next stage became a nuclear decay. More fire! More combustion! More power! That's the driving idea of the mankind. And people do everything to achieve an even more powerful thing - the nuclear fusion. But, can people control it? That's the question is. I hope, we'll can keep it under control... And what is the next step? I don't know, but I think, that it will be the power of annihilation.

[1]  Alternatives:   Today's talk....    or     Our talk of today....