Prevent poisoning.

"There was no ruler or rich character who failed to make his servants taste food and drinks before sitting down at table. Nor was there a Pope, king, prince, cardinal or simple condottiere who did not own a silver ship with unfurled sails, whose The hull was opened with a key, keeping their own cutlery, napkin, salt and all the spices inside, to avoid possible poisoning Every guest at a banquet sent his ship ahead with a faithful servant in charge of placing it in the table, and when he arrived he opened it with his key, taking out the cutlery and the spices, without the owner of the house being offended by such precaution". (Blasco Ibáñez - "At the feet of Venus - The Borgias")

It has been shown that many deaths caused by the legendary Borgia poison were really the result of syphilis, a very widespread disease at the time.