For those who might find it of interest, I pass along, without comment, the following:
In the Mahabharata, Santi Parva, Srila Vyasadeva says, “When the householder beholds wrinkles on his body and grey hair on his head, and children of his children, he should then retire into the forest. The third part of his life [from 50 to 75 years] he should pass in the observance of the vanaprastha mode.”