With his own hand he copied manuscripts referring to Poland and Lithuania wherever he found them and in three years amassed a collection of one hundred and ten folio volumes. Where he was not allowed to copy he read and, on returning home in the evening, wrote out what his prodigious memory retained.
With his own hand, he transcribed manuscripts about Poland and Lithuania that he encountered, accumulating a collection of 110 volumes over three years. Where copying was forbidden, he read the materials and, upon returning home in the evening, recreated what his remarkable memory retained.