'Invidia' (Envy) is one of the Seven Deadly Sins. There are also in medieval typology seven virtues, subdivided (as in the passage quoted from Dante and discussed in note 21 ) into three theological virtues and four cardinal. The greatest of the virtues is 'Charitas' (Charity) — see 1 Corinthians xiii.13. In the Arena Chapel in Padua there is a set of monochrome frescoes by Giotto depicting the virtues and vices. Each letter of 'Fors Clavigera' had a frontispiece, five of which were autotype reproductions of these frescoes. Thus, 'Invidia' was used for Letter 6 and 'Charitas' for Letter 7. Letter 10, as will be seen, had 'Injustitia' (Injustice).