Simplify the following text for a Grade 7 native English-speaking person.
Original: The story of Niobe is an ancient one among Greeks : Niobe is mentioned by Achilles to Priam in Homer 's Iliad book XXIV , as a stock type for mourning .
Simplified: The story of Niobe , and especially her sorrows , is an ancient one . The context in which she is mentioned by Achilles to Priam in Homer 's Iliad is as a stock type for mourning .