Et una ricca stanza nel proprio palagio suo fatta preparare, quelli caramente pregò, che alcun tempo con esso lui fussero contenti di dimorare, accertandoli il meglio, che pote, dalla molta stima, che egli del pronto et alto loro ingegno facea.
1
And he had a sumptuous room prepared in his own palace and he kindly begged them to stay with him as long as they wished, assuring them as best he could of his great esteem for their quick and high intelligence.
Translated by markvanroode 1238 5 years, 5 months ago
0
And he had a sumptuous room prepared in his own palace and he kindly begged them to stay with him as long as they wished, ascertaining them as best he could his great esteem for their quick and high intelligence.
Translated by markvanroode 1238 5 years, 9 months ago

Discussion

Marina, 'accertare' occurs frequently in this text and can be translated by to ascertain, to assess, to detect. In English 'ascertain' means: (1) to find out or learn with certainty, (2) to make certain, exact, or precise, see e.g. https://www.merriam-webster.com/dictionary/ascertain. Your suggestion 'assuring' better represents what is meant here.

by markvanroode 5 years, 5 months ago

assuring them as best he could of his great esteem ???
"ascertain" sounds like the Italian word but I don't think it can have that meaning.

by marina 5 years, 5 months ago