/ Two souls with but a single thought,
Two hearts that beat as one.

Der Sohn der Wildnis (1842), Act ii (published in English as Ingomar the Barbarian; translation by Maria Lovell), reported in Bartlett's Familiar Quotations, 10th ed. (1919). Compare: "Two friends, two bodies with one soul inspir’d", Alexander Pope, The Iliad of Homer, Book xvi, line 267.; "’T was then we luvit ilk ither weel, ’T was then we twa did part: Sweet time—sad time! twa bairns at scule— Twa bairns and but ae heart", William Motherwell, Jeannie Morrison (c. 1832), Stanza 3.