This is the 1983rd most frequent French word.
témoignent
"Testify" or "bear witness."
In this sentence, 'témoignent' is used to indicate how the ruins reflect or give evidence of historical grandeur.
Les ruines antiques témoignent de la grandeur passée de cette civilisation.
The ancient ruins testify to the past greatness of this civilization.
Here, 'témoignent' conveys the demonstration of commitment or dedication by researchers through their actions or conduct.
Les chercheurs témoignent de leur engagement envers la science à travers leurs nombreuses publications.
Researchers demonstrate their commitment to science through their numerous publications.
In this case, 'témoigne' indicates how the calm attitude reveals or expresses confidence.