Lucky yet sad? My friend, should Fortune find You lacking gratitude, she'll change her mind. [Tristis es et felix. Sciat hoc Fortuna caveto: Ingratum dicet te, Lupe, si scierit.] "To Lupus." (Source (Latin)). Alternate translations: Th' art rich & sad; take heed lest fortune know; She 'll call th' unthankefull,…