What is the work of a minister?

A minister of Christ is not an essayist, nor an orator, nor a lecturer, nor a philosopher, but an ‘ambassador for Christ’ (2 Cor. 5.20); a ‘fisher of men’ (Matt.4:19). His work is not in the first place that of improving morals, or elevating character, or rectifying social evils, or redressing material wrongs, – but of SAVING.

– Horatius Bonar, The Life of John Milne of Perth (BoT, 2010)

What is the work of a minister?