(@pork; where in the world did you come up with Slovene or Slovenian (slovenski jezik or slovenščina)? Boswell was English and would have used either Latin or Greek to embellish his writing.)
Two well-known Latin tags are “Ipse dixit,” – Latin for “he himself said it,” meaning something that is asserted but unproved.
And “Ipso facto: “directly translated as “by the deed itself,” which means that a certain effect is a direct consequence of the action in question .
(Ipse, ipsa, ipsum) him, her, itself – nominative case.