Portraits of Gottfried Wilhelm Leibnitz, Sir Isaac Newton and Samuel Clarke, unknown engraver Head and shoulder portraits of three philosophers, all oval: Leibnitz (top), Newton (left), Clarke (right). Set against a panelled wall with drapery and books. Inscribed above the appropriate images: "G.Wil.von Leibnitz", "Isaacus Newton" and "Sam: Clark". early 19th century