Chapter 2 treats filial piety as the first scale on a ladder of public love. The child who learns to align with the heart of parents is not meant to remain enclosed in family duty. That same pattern grows into patriotism, then into saintliness, and finally into divine sonship or daughtership before God.
This makes filial piety more than obedience. It is apprenticeship in how to inherit a heart, carry sorrow, and act for someone larger than the self. In the chapter’s logic, a person who cannot practice faithful love in the family lacks the formation needed for genuinely public love.
There is also a quiet rebuke here for leadership culture. Public authority without filial formation risks becoming ambition with spiritual language.
Book 14 reinforces the same point by insisting that this widening is not metaphorical. Filial piety is meant to take family form and then widen into nation, world, and God without changing its center of love.