S1: The first great discovery that man probably made was that of fire.

S6: The animals were not clever enough to learn anything from this.

P: Fires sometimes occur by themselves in the forests perhaps by rubbing together of flints or something else.

Q: We light a fire now by a match.

R: In olden times fires were made by striking two flints against each other till a spark came for setting fire to a dry thing.

S: But matches are quite recent things.

The proper sequence should be

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