Grandparents continue to play a role in instruction, both with regard to their adult children and their grandchildren. This is easily ignored today, because we think of technical and scientific knowledge as primary, and the elderly are obsolete along with their science and know-how. However, prudential knowledge is never obsolete. Thomas uses teleological explanations based on simple observations of the animal kingdom. We may add another observation.
Human females are unique in that they outlive their own fertility, surviving well past menopause.
The permanence of the family starts with the bond of man and wife, but grows into the bonds of the extended family, which is a broader forum for nurture and education. The Family and the State Thomas recognizes both the family and the state as natural societies. The state makes up for what the family cannot provide. However, the state should not take over the functions that the family can perform well enough by itself. A natural society is one that must come into being because of the necessities of nature.