Posterity: you will never know how much it has cost my generation to preserve your freedom. I hope you will make good use of it.

The line frames political liberty as an inheritance purchased at great cost—through war, sacrifice, and sustained civic labor—by an earlier generation. Addressing “Posterity” turns the statement into a moral appeal: later citizens enjoy freedoms they did not personally win, and therefore bear a duty to steward them responsibly. The second sentence (“I hope you will make good use of it”) shifts from lament to exhortation, implying that freedom can be squandered through apathy, factionalism, or neglect of republican institutions. Whether or not Adams wrote it, the sentiment is characteristic of early American revolutionary memory: liberty is not self-sustaining, and each generation must justify the sacrifices of the last by practicing civic virtue.