There is no remembrance - I believe the general meaning to be this: Multitudes of ancient transactions have been lost, because they were not recorded; and of many that have been recorded, the records are lost. And this will be the case with many others which are yet to occur. How many persons, not much acquainted with books, have supposed that certain things were their own discoveries, which have been written or printed even long before they were born! Dutens, in his Origin of the Discoveries attributed to the Moderns, has made a very clear case.
Things - Rather, men.