Death at the age of sixty is considered to be Divinely ordered: Moed Katan 28a
Even when a person is alive, he is termed "Rimah," "decay": Temurah 31a
Three people are considered at risk of dying, even if they appear healthy - people with intestinal dysfunction, women in labor, and people with Hadroken disease: Eruvin 41b
Using the term "marzeiach מרזח" for a mourner, referring to the mourner's bitter, distracted state, from Yirmiyahu 16:5: Ketuvot 69a-b
Gd forgives the sins of one who mourns for a good person: Shabbat 105b, Moed Katan 25a
One who mourns too much, will soon be mourning another: Moed Katan 27b
During the first three days the mourner should see himself as though there is a sword on his loins, for the next four as though it is opposite him in the corner, and afterwards as though it was passing by in the market: Moed Katan 27b
Gd says to those who mourn for too long, "You are no more merciful than I am!": Moed Katan 27b
Gd counts and saves the tears of one who mourns for a good person: Shabbat 105b
The main bitterness is on the first day: Moed Katan 21a
The rabbis are constantly reminded to mourn for each other, whenever they mention each others' lessons: Moed Katan 24a