In the same way, my Liberalis, as some things remain in our memory as soon as they are learned, while to know others it is not enough to have learned them, for our knowledge slips away from us unless it be kept up — I allude to geometry and astronomy, and such other sciences as are Hard to remember because of their intricacy — so the greatness of some benefits prevents their being forgotten, while others, individually less, though many more in number, and bestowed at different times, pass from our minds, because, as I have stated above, we do not constantly think about them, and do not willingly recognize how much we owe to each of our benefactors.............