Instead . . . of making their feet soft with sandals, Lycurgus enacted that they should harden them by going without sandals; thinking that, if they exercised themselves in this state, they would go up steep places with far greater ease, and descend declivities with greater safety; and that they would also leap, and skip, and run faster unshod, if they had their feet inured to doing so, than shod. Is this an example of verifiable or unverifiable information? Why?